title
DP 34. Wildcard Matching | Recursive to 1D Array Optimisation 🔥

description
Lecture Notes/C++/Java Codes: https://takeuforward.org/dynamic-programming/striver-dp-series-dynamic-programming-problems/ Problem Link: https://bit.ly/3qXtORt Pre-req for this Series: https://www.youtube.com/watch?v=yVdKa8dnKiE&list=PLgUwDviBIf0rGlzIn_7rsaR2FQ5e6ZOL9 a Make sure to join our telegram group for discussions: https://linktr.ee/takeUforward Full Playlist: https://www.youtube.com/watch?v=FfXoiwwnxFw&list=PLgUwDviBIf0qUlt5H_kiKYaNSqJ81PMMY In this video, we solve the wildcard matching problem, which is a leetcode hard problem. If you have not yet checked our SDE sheet, you should definitely do it: https://takeuforward.org/interviews/strivers-sde-sheet-top-coding-interview-problems/ You can also get in touch with me at my social handles: https://linktr.ee/takeUforward

detail
{'title': 'DP 34. Wildcard Matching | Recursive to 1D Array Optimisation 🔥', 'heatmap': [{'end': 1243.728, 'start': 1210.47, 'weight': 1}, {'end': 1869.198, 'start': 1841.109, 'weight': 0.826}, {'end': 2532.752, 'start': 2473.424, 'weight': 0.861}], 'summary': 'Covers wildcard and string matching problems, challenges in string matching with a star, recursion in dynamic programming, recursive pattern matching, indexing conversion, and space optimization in programming and dynamic programming, achieving 100% space efficiency through the use of 1d arrays and an n cross m loop.', 'chapters': [{'end': 281.404, 'segs': [{'end': 95.209, 'src': 'embed', 'start': 23.427, 'weight': 1, 'content': [{'end': 30.252, 'text': 'like you will have characters, but you can have a question mark or you could have a star.', 'start': 23.427, 'duration': 6.825}, {'end': 36.017, 'text': 'okay, now, question mark means matches with single character.', 'start': 30.252, 'duration': 5.765}, {'end': 40.561, 'text': 'remember this it means matches with single character.', 'start': 36.017, 'duration': 4.544}, {'end': 51.27, 'text': 'star means matches with sequence of length 0 or more.', 'start': 40.561, 'duration': 10.709}, {'end': 54.581, 'text': 'Okay, so what does this mean?', 'start': 53.14, 'duration': 1.441}, {'end': 56.343, 'text': 'Let me give you a couple of examples.', 'start': 54.962, 'duration': 1.381}, {'end': 63.629, 'text': 'Assume the string 1 to be question mark AY.', 'start': 56.943, 'duration': 6.686}, {'end': 70.095, 'text': 'Okay, and remember one thing, this question mark or the star will only be in the string S1.', 'start': 63.79, 'duration': 6.305}, {'end': 72.938, 'text': 'It will not be in the string S2.', 'start': 70.516, 'duration': 2.422}, {'end': 76.161, 'text': 'So the string S2 is Ray.', 'start': 73.378, 'duration': 2.783}, {'end': 78.123, 'text': "Okay, now let's see if they match.", 'start': 76.321, 'duration': 1.802}, {'end': 83.177, 'text': 'y, y matches a, a matches.', 'start': 79.333, 'duration': 3.844}, {'end': 90.585, 'text': 'this r is with question mark and it states question mark means it matches with single character.', 'start': 83.177, 'duration': 7.408}, {'end': 92.647, 'text': 'it can match with any single character.', 'start': 90.585, 'duration': 2.062}, {'end': 95.209, 'text': 'so i can say question mark matches with r.', 'start': 92.647, 'duration': 2.562}], 'summary': 'Explains usage of question mark and star in matching characters, with example and explanation.', 'duration': 71.782, 'max_score': 23.427, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo23427.jpg'}, {'end': 165.236, 'src': 'embed', 'start': 128.991, 'weight': 0, 'content': [{'end': 134.115, 'text': 'Star means it can match any sequence.', 'start': 128.991, 'duration': 5.124}, {'end': 135.396, 'text': "So, let's take it.", 'start': 134.575, 'duration': 0.821}, {'end': 142.565, 'text': 'D matches with D, C matches with C, A matches with A, B matches with B.', 'start': 136.622, 'duration': 5.943}, {'end': 152.61, 'text': 'So I can say this star matches with the entire sequence DEF because it states matches with the sequence of length 0 or more.', 'start': 142.565, 'duration': 10.045}, {'end': 156.972, 'text': 'So this star matches with this DEF.', 'start': 152.95, 'duration': 4.022}, {'end': 159.433, 'text': 'So this is definitely true.', 'start': 157.992, 'duration': 1.441}, {'end': 165.236, 'text': 'What if I change the strings and I say what if the string would have been.', 'start': 161.094, 'duration': 4.142}], 'summary': 'The star matches the entire sequence def, confirming its functionality.', 'duration': 36.245, 'max_score': 128.991, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo128991.jpg'}, {'end': 281.404, 'src': 'embed', 'start': 255.959, 'weight': 5, 'content': [{'end': 261.22, 'text': 'given a string s2, which will just have lowercase letters.', 'start': 255.959, 'duration': 5.261}, {'end': 265.881, 'text': 'you need to tell me if the string s1 matches with the string s2 or not.', 'start': 261.22, 'duration': 4.661}, {'end': 272.782, 'text': 'you just need to return me either a true or you just need to return me either a false.', 'start': 265.881, 'duration': 6.901}, {'end': 273.862, 'text': 'you just need me.', 'start': 272.782, 'duration': 1.08}, {'end': 277.743, 'text': 'you just need to make sure you return either of these.', 'start': 273.862, 'duration': 3.881}, {'end': 281.404, 'text': 'so How do you actually proceed with this problem?', 'start': 277.743, 'duration': 3.661}], 'summary': 'Determine if string s1 matches string s2 by returning true or false.', 'duration': 25.445, 'max_score': 255.959, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo255959.jpg'}], 'start': 0.089, 'title': 'Matching problems', 'summary': "Discusses wildcard and string matching problems, explaining the matching criteria using '?' and '*', and providing examples of true and false matches. it presents the requirement to return true or false based on the match.", 'chapters': [{'end': 95.209, 'start': 0.089, 'title': 'Wildcard matching problem', 'summary': 'Presents a problem on wildcard matching where a string with question marks and stars is to be matched with another string, with the question mark representing a single character and the star representing a sequence of length 0 or more.', 'duration': 95.12, 'highlights': ['The problem involves matching strings containing question marks and stars, with the question mark representing a single character and the star representing a sequence of length 0 or more.', 'The star in the string S1 can match with any single character, while the question mark matches with a single character from the other string.', 'The example demonstrates how the question mark and the star in the strings S1 and S2 match with the corresponding characters in the other string.']}, {'end': 281.404, 'start': 95.209, 'title': 'String matching problem', 'summary': "Discusses the concept of matching strings using '*' and '?' characters, explaining the matching criteria and providing examples of true and false matches, and the requirement to return either true or false based on the match.", 'duration': 186.195, 'highlights': ["The '*' character can match any sequence of length 0 or more, allowing flexible pattern matching, as seen in the examples matching 'star' with 'c, d' and 'star star' with 'a, b, c, d'.", "The '?' character can only match a single character, as demonstrated in the example of matching 'A, B, ?' with 'A, B, C' where it fails to match due to the character 'C'.", "The problem involves determining whether a given string 'S1', which may contain lowercase letters, '?', and '*', matches with another string 'S2' consisting of only lowercase letters, and the requirement to return either true or false based on the match."]}], 'duration': 281.315, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo89.jpg', 'highlights': ["The '*' character can match any sequence of length 0 or more, allowing flexible pattern matching, as seen in the examples matching 'star' with 'c, d' and 'star star' with 'a, b, c, d'.", 'The problem involves matching strings containing question marks and stars, with the question mark representing a single character and the star representing a sequence of length 0 or more.', 'The star in the string S1 can match with any single character, while the question mark matches with a single character from the other string.', 'The example demonstrates how the question mark and the star in the strings S1 and S2 match with the corresponding characters in the other string.', "The '?' character can only match a single character, as demonstrated in the example of matching 'A, B, ?' with 'A, B, C' where it fails to match due to the character 'C'.", "The problem involves determining whether a given string 'S1', which may contain lowercase letters, '?', and '*', matches with another string 'S2' consisting of only lowercase letters, and the requirement to return either true or false based on the match."]}, {'end': 520.409, 'segs': [{'end': 358.122, 'src': 'embed', 'start': 308.795, 'weight': 0, 'content': [{'end': 312.096, 'text': 'Where is the main problem? The main problem arises.', 'start': 308.795, 'duration': 3.301}, {'end': 318.479, 'text': "Yes, the main problem arises if it is a star because for question mark, it's very straightforward.", 'start': 312.136, 'duration': 6.343}, {'end': 319.08, 'text': 'They will match.', 'start': 318.519, 'duration': 0.561}, {'end': 322.921, 'text': 'But for star is when the problem arises.', 'start': 319.52, 'duration': 3.401}, {'end': 325.663, 'text': 'So let us take an example and understand.', 'start': 323.262, 'duration': 2.401}, {'end': 334.188, 'text': 'Assume you had AB star CD, you had AB DEF CD.', 'start': 326.523, 'duration': 7.665}, {'end': 344.295, 'text': "so when you're matching you'll be like D matches with D, C matches with C, but for the star you exactly don't know how many will match,", 'start': 334.188, 'duration': 10.107}, {'end': 346.176, 'text': 'because you know B matches with B.', 'start': 344.295, 'duration': 1.881}, {'end': 355.121, 'text': "but for the star you have to be very critical whether you'll take this F or whether you'll take ef, whether you'll take def,", 'start': 346.176, 'duration': 8.945}, {'end': 358.122, 'text': "whether you'll take bdf or whether you'll take a.", 'start': 355.121, 'duration': 3.001}], 'summary': 'The main problem arises in matching patterns with a star due to uncertainty of matches.', 'duration': 49.327, 'max_score': 308.795, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo308795.jpg'}, {'end': 433.163, 'src': 'embed', 'start': 406.805, 'weight': 2, 'content': [{'end': 416.654, 'text': 'You have to try all possible ways and whenever a question comes across all possible ways, what comes to your brain?', 'start': 406.805, 'duration': 9.849}, {'end': 420.074, 'text': 'definitely, recursion.', 'start': 418.393, 'duration': 1.681}, {'end': 421.895, 'text': 'i will try recursion.', 'start': 420.074, 'duration': 1.821}, {'end': 424.997, 'text': 'string matching by recursion is what i will try.', 'start': 421.895, 'duration': 3.102}, {'end': 427.559, 'text': 'i will try out every possible portion.', 'start': 424.997, 'duration': 2.562}, {'end': 430.641, 'text': 'perfect. so rules to write the recursion come on.', 'start': 427.559, 'duration': 3.082}, {'end': 431.462, 'text': "that's very simple.", 'start': 430.641, 'duration': 0.821}, {'end': 433.163, 'text': 'now, what are the rules?', 'start': 431.462, 'duration': 1.701}], 'summary': 'Recursion is the preferred approach for trying all possible ways in string matching.', 'duration': 26.358, 'max_score': 406.805, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo406805.jpg'}], 'start': 281.844, 'title': 'Challenges in string matching', 'summary': 'Discusses the challenges of string matching with a star, emphasizing the need for trial and error when determining the number of matches, and the use of recursion in string matching, illustrated with an example of ab*cd matching abdefcd and explained in lecture 6 of the recursion series.', 'chapters': [{'end': 406.385, 'start': 281.844, 'title': 'String matching with star problem', 'summary': 'Discusses the challenges of string matching with a star, emphasizing the need for trial and error when determining the number of matches, illustrated with an example of ab*cd matching abdefcd.', 'duration': 124.541, 'highlights': ['The main problem arises when dealing with a star in string matching, as determining the number of matches becomes critical and requires trial and error, demonstrated through the example of AB*CD matching ABDEFCD.', 'In string matching with a star, the process of determining the correct number of matches involves trial and error, where attempting various scenarios such as taking 0, 1, 2, 3, or 4 matches is necessary to accurately determine the correct matching sequence.']}, {'end': 520.409, 'start': 406.805, 'title': 'Recursion in string matching', 'summary': 'Discusses the use of recursion in string matching, emphasizing the rules for writing recursion and the standard pattern for returning true or false in solving problems, as explained in lecture 6 of the recursion series.', 'duration': 113.604, 'highlights': ['The standard pattern for returning true or false in solving problems is straightforward: in the base case, either return true or false; if there are multiple states, return true if one returns true, and return false if both return false.', 'The chapter emphasizes the rules for writing recursion when comparing two strings, expressing them in terms of i and j, and exploring comparisons to determine the possibility of returning true.', 'The discussion highlights the use of recursion in string matching and the approach of trying out every possible portion to find a solution.']}], 'duration': 238.565, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo281844.jpg', 'highlights': ['Determining the correct number of matches in string matching with a star involves trial and error', 'The process of determining the correct number of matches in string matching with a star requires attempting various scenarios', 'The chapter emphasizes the rules for writing recursion when comparing two strings', 'The main problem in string matching arises when dealing with a star, as determining the number of matches becomes critical']}, {'end': 868.716, 'segs': [{'end': 557.162, 'src': 'embed', 'start': 520.409, 'weight': 2, 'content': [{'end': 523.231, 'text': 'so how do you actually solve this problem?', 'start': 520.409, 'duration': 2.822}, {'end': 529.958, 'text': "so let's analyze f of i j, But we need to figure out what is f of i j.", 'start': 523.231, 'duration': 6.727}, {'end': 530.338, 'text': "Let's see.", 'start': 529.958, 'duration': 0.38}, {'end': 535.22, 'text': "I'll be like what if I write n minus 1 and m minus 1?", 'start': 531.198, 'duration': 4.022}, {'end': 536.92, 'text': 'What does this signify?', 'start': 535.22, 'duration': 1.7}, {'end': 548.184, 'text': 'This signifies nothing, but if the string is ab star cd and the length is nothing but 0, 1, 2, 3, 4..', 'start': 537.601, 'duration': 10.583}, {'end': 557.162, 'text': 'So f of 4 comma ab def cd 0, 1, 2, 3, 4, 5, 6, 7.', 'start': 548.184, 'duration': 8.978}], 'summary': "Analyzing f(i,j) with string 'ab star cd' and length 0-7.", 'duration': 36.753, 'max_score': 520.409, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo520409.jpg'}, {'end': 672.962, 'src': 'embed', 'start': 645.982, 'weight': 3, 'content': [{'end': 655.195, 'text': "What are these two conditions? You can be like, if S of 1 of I matches with S of 2 of J, that's definitely one of the conditions.", 'start': 645.982, 'duration': 9.213}, {'end': 666.339, 'text': 'and the other condition is if this is equal to equal to question mark, then also i can say question mark does match with anything on s2 of j,', 'start': 656.016, 'duration': 10.323}, {'end': 668.38, 'text': 'which is, this is not and this will be.', 'start': 666.339, 'duration': 2.041}, {'end': 672.962, 'text': 'or, or if either of these cases are true, they are matching.', 'start': 668.38, 'duration': 4.582}], 'summary': "Conditions are: s1 of i matches s2 of j and '?' matches anything on s2 of j.", 'duration': 26.98, 'max_score': 645.982, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo645982.jpg'}, {'end': 726.426, 'src': 'embed', 'start': 698.98, 'weight': 1, 'content': [{'end': 704.722, 'text': "let's reduce our i, let's reduce our j and look for the smaller strings if they can be matched or not.", 'start': 698.98, 'duration': 5.742}, {'end': 707.297, 'text': 'we solved This was the bigger problem.', 'start': 704.722, 'duration': 2.575}, {'end': 712.76, 'text': 'We solved a portion of it and we are asking the smaller portion to be solved by the recursion.', 'start': 707.658, 'duration': 5.102}, {'end': 715.761, 'text': "Okay So, that's what this will be doing.", 'start': 713.18, 'duration': 2.581}, {'end': 717.082, 'text': 'Return Okay.', 'start': 716.001, 'duration': 1.081}, {'end': 720.043, 'text': "What can be the other condition? Let's analyze.", 'start': 717.442, 'duration': 2.601}, {'end': 726.426, 'text': 'The other condition that I can think of is what if my I.', 'start': 721.504, 'duration': 4.922}], 'summary': 'Solving a portion of a larger problem and using recursion for the smaller portion. analyzing conditions.', 'duration': 27.446, 'max_score': 698.98, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo698980.jpg'}, {'end': 810.958, 'src': 'embed', 'start': 781.663, 'weight': 0, 'content': [{'end': 782.584, 'text': 'That can be one of the cases.', 'start': 781.663, 'duration': 0.921}, {'end': 789.165, 'text': "Or I can say, let's match EF and still stand at I.", 'start': 785.004, 'duration': 4.161}, {'end': 791.546, 'text': 'So, I can actually match 0.', 'start': 789.165, 'duration': 2.381}, {'end': 792.666, 'text': 'I can actually match 1.', 'start': 791.546, 'duration': 1.12}, {'end': 793.827, 'text': 'I can actually match 2.', 'start': 792.666, 'duration': 1.161}, {'end': 794.827, 'text': 'I can actually match 3.', 'start': 793.827, 'duration': 1}, {'end': 796.327, 'text': 'I can actually match 4.', 'start': 794.827, 'duration': 1.5}, {'end': 799.308, 'text': 'I can match any number of characters for this term.', 'start': 796.327, 'duration': 2.981}, {'end': 801.389, 'text': 'Yes, any number of characters for this term.', 'start': 799.528, 'duration': 1.861}, {'end': 804.677, 'text': 'so i can either go that way.', 'start': 802.156, 'duration': 2.521}, {'end': 810.958, 'text': "probably i'll try to write a recursion so that that way is also taken care of easily.", 'start': 804.677, 'duration': 6.281}], 'summary': 'Matching various numbers of characters for a term using recursion.', 'duration': 29.295, 'max_score': 781.663, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo781663.jpg'}], 'start': 520.409, 'title': 'String matching and recursion', 'summary': 'Discusses various string matching conditions and techniques, such as direct character match, question mark matching, recursion in dynamic programming, and handling the star symbol, offering insights into the process of shrinking strings and solving smaller portions of the problem.', 'chapters': [{'end': 672.962, 'start': 520.409, 'title': 'String matching conditions', 'summary': 'Discusses the function f(i,j) which signifies whether two strings of lengths i and j are matching or not, and it explores the conditions for matching including direct character match and matching with a question mark.', 'duration': 152.553, 'highlights': ['The function f(i,j) signifies whether two strings of lengths i and j are matching or not, with the example of f(4,6) indicating matching of strings from 0 to 4 and 0 to 6.', 'The conditions for matching include direct character match between S1[i] and S2[j] and the matching of a question mark with any character in S2[j].', 'The analysis of the function f(i,j) includes identifying the base case and exploring scenarios of direct character match and matching with a question mark.']}, {'end': 720.043, 'start': 672.962, 'title': 'String matching and recursion', 'summary': 'Discusses string matching and recursion in dynamic programming, emphasizing the process of shrinking strings and solving smaller portions of the problem through recursion.', 'duration': 47.081, 'highlights': ['The process involves shrinking strings and solving smaller portions of the problem through recursion.', 'Matching of strings is a key focus, emphasizing the condition of matching and reducing the strings for further analysis.', 'The chapter highlights the simplicity of the process and the iterative nature of matching conditions right from the beginning of dynamic programming on strings.']}, {'end': 868.716, 'start': 721.504, 'title': 'Handling star symbol in string matching', 'summary': 'Discusses handling the star symbol in string matching, exploring scenarios of matching zero, one, or multiple characters with the star symbol and the possibility of recursion to handle multiple character matches.', 'duration': 147.212, 'highlights': ["The chapter explores scenarios of matching zero, one, or multiple characters with the star symbol, depicting the flexibility of matching any number of characters for the term, providing a comprehensive understanding of the star symbol's functionality.", "The discussion includes handling the star symbol as 'nothing' and the subsequent reduction of characters, emphasizing the case where the star means nothing and its impact on the string matching process.", 'The possibility of recursion to handle multiple character matches is considered, indicating the potential strategy of writing a recursion to efficiently handle such scenarios.', "The concept of the star symbol being equivalent to 'nothing' is reiterated, underlining its impact on reducing characters and ensuring its consideration in the string matching process."]}], 'duration': 348.307, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo520409.jpg', 'highlights': ["The chapter explores scenarios of matching zero, one, or multiple characters with the star symbol, depicting the flexibility of matching any number of characters for the term, providing a comprehensive understanding of the star symbol's functionality.", 'The process involves shrinking strings and solving smaller portions of the problem through recursion.', 'The function f(i,j) signifies whether two strings of lengths i and j are matching or not, with the example of f(4,6) indicating matching of strings from 0 to 4 and 0 to 6.', 'The conditions for matching include direct character match between S1[i] and S2[j] and the matching of a question mark with any character in S2[j].']}, {'end': 1966.599, 'segs': [{'end': 1243.728, 'src': 'heatmap', 'start': 1210.47, 'weight': 1, 'content': [{'end': 1212.091, 'text': 'this is neither a star.', 'start': 1210.47, 'duration': 1.621}, {'end': 1214.472, 'text': 'this is not a star, not a question mark.', 'start': 1212.091, 'duration': 2.381}, {'end': 1216.092, 'text': 'so this is not matching.', 'start': 1214.472, 'duration': 1.62}, {'end': 1217.833, 'text': 'you cannot match them.', 'start': 1216.092, 'duration': 1.741}, {'end': 1225.636, 'text': 'so at the end of the day, if either the strings have to be matching, it has to be question mark, or it has to be a star.', 'start': 1217.833, 'duration': 7.803}, {'end': 1227.736, 'text': 'otherwise you cannot match.', 'start': 1225.636, 'duration': 2.1}, {'end': 1235.459, 'text': "and if you cannot match, let's return a true, perfect return to true, amazing.", 'start': 1227.736, 'duration': 7.723}, {'end': 1243.728, 'text': "so that's how I have explored comparisons expressed as well, out of all comparison.", 'start': 1235.459, 'duration': 8.269}], 'summary': 'String comparison requires match with star or question mark for success.', 'duration': 33.258, 'max_score': 1210.47, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo1210470.jpg'}, {'end': 1398.002, 'src': 'embed', 'start': 1370.949, 'weight': 3, 'content': [{'end': 1375.152, 'text': "So before going to string 2 gets exhausted, if this is the case, it's fine.", 'start': 1370.949, 'duration': 4.203}, {'end': 1384.277, 'text': 'But if just the string got exhausted, if just the string got exhausted and the other string did not get exhausted,', 'start': 1375.712, 'duration': 8.565}, {'end': 1387.359, 'text': 'which means the J is still greater than or equal to 0..', 'start': 1384.277, 'duration': 3.082}, {'end': 1389.2, 'text': 'So there are some comparisons still left.', 'start': 1387.359, 'duration': 1.841}, {'end': 1390.381, 'text': 'So return false.', 'start': 1389.34, 'duration': 1.041}, {'end': 1395.042, 'text': 'But there can be the other way where I say, hey listen, hey listen.', 'start': 1391.221, 'duration': 3.821}, {'end': 1398.002, 'text': 'The j is lesser than 0.', 'start': 1395.862, 'duration': 2.14}], 'summary': 'Examining string exhaustion and comparisons, return false based on conditions.', 'duration': 27.053, 'max_score': 1370.949, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo1370949.jpg'}, {'end': 1574.564, 'src': 'embed', 'start': 1550.494, 'weight': 2, 'content': [{'end': 1558.526, 'text': "i'll write that in the code, but before that, uh, let me just quickly work you through the time complexity.", 'start': 1550.494, 'duration': 8.032}, {'end': 1560.147, 'text': "obviously it's recursion.", 'start': 1558.526, 'duration': 1.621}, {'end': 1566.334, 'text': "so you're going to try out all matchings and it is definitely going to be exponential.", 'start': 1560.147, 'duration': 6.187}, {'end': 1573.723, 'text': "again you're doing with asterix, so they can be 0, 1, 2, so the time complexity will be exponential.", 'start': 1566.334, 'duration': 7.389}, {'end': 1574.564, 'text': 'that is what i can say.', 'start': 1573.723, 'duration': 0.841}], 'summary': 'Recursion leads to exponential time complexity when trying all matchings with asterisks.', 'duration': 24.07, 'max_score': 1550.494, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo1550494.jpg'}, {'end': 1633.856, 'src': 'embed', 'start': 1602.193, 'weight': 1, 'content': [{'end': 1607.557, 'text': 'i, j, what is the maximum possible value of i, n, minus one?', 'start': 1602.193, 'duration': 5.364}, {'end': 1618.905, 'text': 'so an n, cross m, dp is what you require and you can memorize and the time complexity after memory action will reduce to b, go of n into m,', 'start': 1607.557, 'duration': 11.348}, {'end': 1629.031, 'text': 'because those many will be the number of different states and the space complexity will be n into m plus plus.', 'start': 1618.905, 'duration': 10.126}, {'end': 1633.856, 'text': 'we go of n plus m, which is the auxiliary stack space.', 'start': 1629.031, 'duration': 4.825}], 'summary': 'Find max value of i, n-1. use n x m dp to reduce time complexity to o(n*m) and space complexity to n+m.', 'duration': 31.663, 'max_score': 1602.193, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo1602193.jpg'}, {'end': 1831.908, 'src': 'embed', 'start': 1798.154, 'weight': 0, 'content': [{'end': 1801.156, 'text': 'we have to actually convert this into a dynamic programming.', 'start': 1798.154, 'duration': 3.002}, {'end': 1806.56, 'text': "so let's quickly do this into a dynamic programming, which is DP of n cross vector of int.", 'start': 1801.156, 'duration': 5.404}, {'end': 1810.544, 'text': 'again, you can definitely write m, cross minus 1.', 'start': 1806.56, 'duration': 3.984}, {'end': 1811.424, 'text': "that's what you have written.", 'start': 1810.544, 'duration': 0.88}, {'end': 1814.166, 'text': 'okay, looks like.', 'start': 1811.424, 'duration': 2.742}, {'end': 1815.908, 'text': 'we just need to declare this right above this.', 'start': 1814.166, 'duration': 1.742}, {'end': 1820.636, 'text': 'at least, make sure you pass on the DP and over here.', 'start': 1817.492, 'duration': 3.144}, {'end': 1831.908, 'text': 'just make sure you carry on the DP as well and write before returning every time, just before calling other functions.', 'start': 1820.636, 'duration': 11.272}], 'summary': 'Converting code to dynamic programming, dp of n cross vector of int.', 'duration': 33.754, 'max_score': 1798.154, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo1798154.jpg'}, {'end': 1869.198, 'src': 'heatmap', 'start': 1841.109, 'weight': 0.826, 'content': [{'end': 1843.27, 'text': 'rightly store the value before returning.', 'start': 1841.109, 'duration': 2.161}, {'end': 1843.85, 'text': 'over here again.', 'start': 1843.27, 'duration': 0.58}, {'end': 1845.75, 'text': 'rightly store the value before returning.', 'start': 1843.85, 'duration': 1.9}, {'end': 1848.511, 'text': 'so if we just do this, it should be fine.', 'start': 1845.75, 'duration': 2.761}, {'end': 1853.292, 'text': 'we need to make sure dp is passed every time we call it.', 'start': 1848.511, 'duration': 4.781}, {'end': 1854.532, 'text': 'please make sure you do that.', 'start': 1853.292, 'duration': 1.24}, {'end': 1857.814, 'text': 'so the vector has not been declared.', 'start': 1856.494, 'duration': 1.32}, {'end': 1865.897, 'text': 'so please make sure you declare hash, include bits, slash, std plus c plus plus dot h.', 'start': 1857.814, 'duration': 8.083}, {'end': 1867.878, 'text': 'we are getting a 100 score.', 'start': 1865.897, 'duration': 1.981}, {'end': 1869.198, 'text': 'that is indeed amazing.', 'start': 1867.878, 'duration': 1.32}], 'summary': 'Ensure proper value storage before returning, pass dp every time, declare hash and achieve a perfect 100 score.', 'duration': 28.089, 'max_score': 1841.109, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo1841109.jpg'}, {'end': 1932.875, 'src': 'embed', 'start': 1901.949, 'weight': 4, 'content': [{'end': 1904.35, 'text': 'Rule number three, copy the recurrence.', 'start': 1901.949, 'duration': 2.401}, {'end': 1907.451, 'text': 'Rule number four is return whatever call you made.', 'start': 1905.29, 'duration': 2.161}, {'end': 1908.131, 'text': "That's it.", 'start': 1907.911, 'duration': 0.22}, {'end': 1913.648, 'text': "Base case is something, once you've done this, these are just plain.", 'start': 1909.867, 'duration': 3.781}, {'end': 1916.89, 'text': "Okay, what is the base case? Let's go back into the code.", 'start': 1913.989, 'duration': 2.901}, {'end': 1922.111, 'text': "So, if you see in the code, you're doing i less than 0, less than 0 again.", 'start': 1917.63, 'duration': 4.481}, {'end': 1929.134, 'text': "So, do you remember in all the previous matching of strings, like if you haven't seen them, please go back and watch it.", 'start': 1922.732, 'duration': 6.402}, {'end': 1932.875, 'text': 'In all the previous lectures.', 'start': 1930.474, 'duration': 2.401}], 'summary': 'Recurrence and base case rules discussed. no quantifiable data.', 'duration': 30.926, 'max_score': 1901.949, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo1901949.jpg'}], 'start': 870.413, 'title': 'Recursive pattern matching', 'summary': 'Explores using recursion to match patterns, with examples of eliminating characters and analyzing base cases. it discusses the conditions for string exhaustion and comparison. it also explains the recursive approach for pattern matching, discussing time and space complexity, and achieving a 100 score.', 'chapters': [{'end': 1269.94, 'start': 870.413, 'title': 'String matching recursion', 'summary': 'Explores using recursion to match patterns, with examples of eliminating characters and analyzing base cases, resulting in a comprehensive approach to string matching with deletions.', 'duration': 399.527, 'highlights': ['The process of using recursion to match patterns includes eliminating characters and analyzing base cases, resulting in a comprehensive approach to string matching with deletions.', 'The detailed analysis involves examples of eliminating characters and the base case, providing a thorough understanding of the process.', 'Exploring comparisons expressed through examples of eliminating characters and analyzing base cases, showcasing the versatility of the approach.', 'Highlighting the importance of base cases and the thought process involved in determining them for effective string matching.', 'The concept of using recursion to match patterns is exemplified through examples of eliminating characters and analyzing base cases.']}, {'end': 1465.085, 'start': 1269.94, 'title': 'String exhaustion and comparison', 'summary': 'Discusses the conditions for string exhaustion and comparison, highlighting the need for both strings to be exhausted for the comparison to be successful, and the possibility of matching a string with an empty string when it contains only asterisks.', 'duration': 195.145, 'highlights': ['Both strings must be exhausted for the comparison to be successful, indicated by i < 0 and j < 0.', 'If the second string is exhausted but the first string still has characters, it returns false.', 'If the first string still has characters and the second string is exhausted, it can match with an empty string only if it contains only asterisks.']}, {'end': 1966.599, 'start': 1465.085, 'title': 'Recursive pattern matching', 'summary': 'Explains the recursive approach for pattern matching, discussing time and space complexity, introducing memoization and transitioning to dynamic programming to optimize the solution, achieving a 100 score.', 'duration': 501.514, 'highlights': ['The time complexity of the recursive approach for pattern matching is exponential as it tries out all possible matchings, especially with asterisks, resulting in 0, 1, 2 possibilities, leading to a space complexity of auxiliary stack space around n + m.', 'Memoization is introduced to address overlapping subproblems by using changing parameters i and j, resulting in the reduction of time complexity to O(n*m) and space complexity to n*m + n + m for the auxiliary stack space.', 'The solution is transitioned to dynamic programming to optimize the approach, achieving a 100 score, and the code is converted into tabulation following the rules of writing base cases, changing parameters, copying the recurrence, and returning the call made.', 'The importance of one-based indexing is emphasized to prevent negative values, and it is noted that understanding previous related videos is crucial for comprehending the explanations provided.', 'The base cases for the recursive approach involve scenarios where both strings are exhausted, one string is exhausted while the other remains, and checking if pattern[i] matches text[j] or if pattern[i] is equal to a question mark, with the additional consideration for the asterisk symbol.']}], 'duration': 1096.186, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo870413.jpg', 'highlights': ['The solution transitions to dynamic programming, achieving a 100 score and optimizing the approach.', 'Memoization reduces time complexity to O(n*m) and space complexity to n*m + n + m.', 'The recursive approach for pattern matching has exponential time complexity and auxiliary stack space around n + m.', 'Both strings must be exhausted for successful comparison, indicated by i < 0 and j < 0.', 'The process of using recursion to match patterns includes eliminating characters and analyzing base cases.']}, {'end': 2307.31, 'segs': [{'end': 1992.631, 'src': 'embed', 'start': 1967.98, 'weight': 3, 'content': [{'end': 1973.584, 'text': 'And this will be simply greater than 0 because you have done one-based indexing.', 'start': 1967.98, 'duration': 5.604}, {'end': 1977.586, 'text': 'Over here, it will be equal to equal to 0 and instead of greater than equal to, it will be just this.', 'start': 1973.604, 'duration': 3.982}, {'end': 1982.768, 'text': 'And what about here? You are traversing, yes.', 'start': 1978.847, 'duration': 3.921}, {'end': 1984.369, 'text': "That's a one-based indexing.", 'start': 1983.248, 'duration': 1.121}, {'end': 1986.569, 'text': 'So, you have to traverse from one creator.', 'start': 1984.409, 'duration': 2.16}, {'end': 1988.41, 'text': 'Yes, you have to traverse from one creator.', 'start': 1986.929, 'duration': 1.481}, {'end': 1992.631, 'text': 'And you have to just go across doing till I.', 'start': 1988.97, 'duration': 3.661}], 'summary': 'Using one-based indexing, traverse from one creator till i.', 'duration': 24.651, 'max_score': 1967.98, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo1967980.jpg'}, {'end': 2040.886, 'src': 'embed', 'start': 2012.959, 'weight': 5, 'content': [{'end': 2015.521, 'text': 'What about here? You look for one lesser because one base indexing guys.', 'start': 2012.959, 'duration': 2.562}, {'end': 2017.923, 'text': 'And right over here, again one lesser.', 'start': 2016.441, 'duration': 1.482}, {'end': 2019.444, 'text': 'I think this should be fine.', 'start': 2018.523, 'duration': 0.921}, {'end': 2023.316, 'text': "So, you see it is giving correct answers, but I'll not submit this.", 'start': 2021.055, 'duration': 2.261}, {'end': 2026.118, 'text': 'And make sure you do it n plus 1, n plus 1.', 'start': 2024.177, 'duration': 1.941}, {'end': 2028.739, 'text': "Perfect So, that's how you convert this into a one-based indexing.", 'start': 2026.118, 'duration': 2.621}, {'end': 2034.262, 'text': 'Now, what am I seeing? i equal to 0, j equal to 0, right? And that has to be returned true.', 'start': 2029.139, 'duration': 5.123}, {'end': 2037.484, 'text': "So, let's convert this case into tabulation.", 'start': 2034.763, 'duration': 2.721}, {'end': 2040.886, 'text': "So, I'll just go over here and I'll say, okay, this will be 0.", 'start': 2037.984, 'duration': 2.902}], 'summary': 'Discussion on converting to one-based indexing and tabulation for i=0, j=0 case.', 'duration': 27.927, 'max_score': 2012.959, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo2012959.jpg'}, {'end': 2256.305, 'src': 'embed', 'start': 2227.822, 'weight': 0, 'content': [{'end': 2230.664, 'text': 'so the following statements will be executed.', 'start': 2227.822, 'duration': 2.842}, {'end': 2236.401, 'text': "else okay, let's just make sure you have something like else.", 'start': 2232.1, 'duration': 4.301}, {'end': 2240.842, 'text': 'if, because the following statements will be executed so over here, what will wait?', 'start': 2236.401, 'duration': 4.441}, {'end': 2242.482, 'text': 'dp of i minus 1, j minus 1.', 'start': 2240.842, 'duration': 1.64}, {'end': 2244.122, 'text': 'perfect. so like, write it.', 'start': 2242.482, 'duration': 1.64}, {'end': 2245.983, 'text': 'dp of i minus 1 and j minus 1.', 'start': 2244.122, 'duration': 1.861}, {'end': 2247.123, 'text': 'amazing over here.', 'start': 2245.983, 'duration': 1.14}, {'end': 2249.443, 'text': 'dp of i minus 1 and j.', 'start': 2247.123, 'duration': 2.32}, {'end': 2256.305, 'text': 'if you have i minus 1 and j, or dp of i and j minus 1, perfect.', 'start': 2249.443, 'duration': 6.862}], 'summary': 'Discussion on executing statements and using dp with i and j', 'duration': 28.483, 'max_score': 2227.822, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo2227822.jpg'}], 'start': 1967.98, 'title': 'Indexing conversion and tabulation for dp', 'summary': 'Covers the conversion of zero-based indexing to one-based indexing and the process of converting a dynamic programming problem into tabulation, emphasizing traversal adjustments and achieving successful code submission with space optimization.', 'chapters': [{'end': 2028.739, 'start': 1967.98, 'title': 'One-based indexing conversion', 'summary': 'Discusses the conversion of zero-based indexing to one-based indexing, emphasizing the traversal and adjustments to look for one lesser in the context of programming.', 'duration': 60.759, 'highlights': ['The conversion of zero-based indexing to one-based indexing is discussed, highlighting the adjustments required for traversal and looking for one lesser.', 'Emphasis is placed on the traversal and adjustments needed to account for one-based indexing, ensuring correct answers in programming.', 'The importance of making n plus 1 adjustments for one-based indexing is emphasized for correct implementation.']}, {'end': 2307.31, 'start': 2029.139, 'title': 'Tabulation for dp problem', 'summary': 'Explains the process of converting a dynamic programming problem into tabulation, with detailed steps and code explanations, achieving a successful code submission and space optimization.', 'duration': 278.171, 'highlights': ['The chapter thoroughly explains the conversion of a dynamic programming problem into tabulation, providing detailed steps and code explanations. It also achieves a successful code submission and space optimization, ensuring a comprehensive understanding of the process.', 'The speaker discusses the process of converting the dynamic programming problem into tabulation, emphasizing the steps and code explanations, leading to a successful code submission and space optimization, highlighting the importance of a comprehensive understanding of the process.', 'The detailed process of converting a dynamic programming problem into tabulation is presented, with a focus on the steps, code explanations, successful code submission, and space optimization, ensuring a comprehensive understanding of the process.', 'The chapter provides a thorough explanation of the process of converting a dynamic programming problem into tabulation, including detailed steps and code explanations, ultimately achieving a successful code submission and space optimization, ensuring a comprehensive understanding of the process.']}], 'duration': 339.33, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo1967980.jpg', 'highlights': ['The chapter thoroughly explains the conversion of a dynamic programming problem into tabulation, providing detailed steps and code explanations. It also achieves a successful code submission and space optimization, ensuring a comprehensive understanding of the process.', 'The detailed process of converting a dynamic programming problem into tabulation is presented, with a focus on the steps, code explanations, successful code submission, and space optimization, ensuring a comprehensive understanding of the process.', 'The speaker discusses the process of converting the dynamic programming problem into tabulation, emphasizing the steps and code explanations, leading to a successful code submission and space optimization, highlighting the importance of a comprehensive understanding of the process.', 'Emphasis is placed on the traversal and adjustments needed to account for one-based indexing, ensuring correct answers in programming.', 'The conversion of zero-based indexing to one-based indexing is discussed, highlighting the adjustments required for traversal and looking for one lesser.', 'The importance of making n plus 1 adjustments for one-based indexing is emphasized for correct implementation.']}, {'end': 2622.581, 'segs': [{'end': 2349.549, 'src': 'embed', 'start': 2308.376, 'weight': 1, 'content': [{'end': 2310.439, 'text': 'We definitely can space optimize this.', 'start': 2308.376, 'duration': 2.063}, {'end': 2320.351, 'text': "Why?? Because again, you're dependent on I minus 1,, which is the previous guy, and you're dependent on I minus 1, again the previous and the current guys.", 'start': 2310.939, 'duration': 9.412}, {'end': 2322.573, 'text': 'So you can definitely space optimize this.', 'start': 2320.871, 'duration': 1.702}, {'end': 2330.379, 'text': "But what are the problems that you'll face? First problem that you'll face is you have to declare the base cases.", 'start': 2323.393, 'duration': 6.986}, {'end': 2333.382, 'text': 'So it will become a bit tricky.', 'start': 2330.96, 'duration': 2.422}, {'end': 2339.688, 'text': "So if you have solved the problem till here, I'll recommend you to try the space optimization by yourself.", 'start': 2334.103, 'duration': 5.585}, {'end': 2343.061, 'text': "and if you do like, i'll explain the space optimization now.", 'start': 2340.618, 'duration': 2.443}, {'end': 2346.946, 'text': "but if you don't understand, there's nothing to worry with time.", 'start': 2343.061, 'duration': 3.885}, {'end': 2349.549, 'text': "probably try it out by yourself, you'll understand.", 'start': 2346.946, 'duration': 2.603}], 'summary': 'Space optimization possible, but base cases need declaration. try space optimization first.', 'duration': 41.173, 'max_score': 2308.376, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo2308376.jpg'}, {'end': 2532.752, 'src': 'heatmap', 'start': 2473.424, 'weight': 0.861, 'content': [{'end': 2474.724, 'text': 'so you will have.', 'start': 2473.424, 'duration': 1.3}, {'end': 2478.745, 'text': 'every time you are at curve, you have to take care of this.', 'start': 2474.724, 'duration': 4.021}, {'end': 2483.006, 'text': 'in the next time, whenever you go to the curve, you again have to assign this.', 'start': 2478.745, 'duration': 4.261}, {'end': 2484.986, 'text': 'next time again you have to assign this.', 'start': 2483.006, 'duration': 1.98}, {'end': 2487.607, 'text': 'so at every junction you have to assign.', 'start': 2484.986, 'duration': 2.621}, {'end': 2490.66, 'text': 'so i know This is the row.', 'start': 2487.607, 'duration': 3.053}, {'end': 2492.141, 'text': 'So this row is already running.', 'start': 2490.9, 'duration': 1.241}, {'end': 2499.145, 'text': 'Just make sure before entering, before starting off, assign it.', 'start': 2492.782, 'duration': 6.363}, {'end': 2503.748, 'text': 'Before starting off, assign the curve every time.', 'start': 2499.705, 'duration': 4.043}, {'end': 2507.83, 'text': 'For every row, just make sure you assign the curve every time.', 'start': 2503.768, 'duration': 4.062}, {'end': 2512.993, 'text': 'And then you can easily start off by saying, okay, this is what the previous will be.', 'start': 2508.35, 'duration': 4.643}, {'end': 2517.135, 'text': 'This is what the previous will be.', 'start': 2514.674, 'duration': 2.461}, {'end': 2518.576, 'text': 'This is the curve over here.', 'start': 2517.155, 'duration': 1.421}, {'end': 2522.078, 'text': 'this is definitely going to be the curve.', 'start': 2519.895, 'duration': 2.183}, {'end': 2532.752, 'text': 'this is definitely going to be the curve right and this is going to be the curve and right at the end you can say previous will be equal to curl and over here you can say previous,', 'start': 2522.078, 'duration': 10.674}], 'summary': 'Assign the curve at every junction to ensure safety and continuity.', 'duration': 59.328, 'max_score': 2473.424, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo2473424.jpg'}, {'end': 2622.581, 'src': 'embed', 'start': 2551.892, 'weight': 0, 'content': [{'end': 2555.937, 'text': 'so guys, go step by step and you do space optimization.', 'start': 2551.892, 'duration': 4.045}, {'end': 2561.601, 'text': "i know it's a bit tricky, it's a bit tough, But I'll always recommend try to do on pen and paper.", 'start': 2555.937, 'duration': 5.664}, {'end': 2563.361, 'text': 'Try to see what base cases you are writing.', 'start': 2561.661, 'duration': 1.7}, {'end': 2565.721, 'text': 'I went step by step and I converted it.', 'start': 2563.861, 'duration': 1.86}, {'end': 2567.422, 'text': 'I did not do a lot of things.', 'start': 2566.261, 'duration': 1.161}, {'end': 2569.602, 'text': 'I just went step by step and I converted it.', 'start': 2567.462, 'duration': 2.14}, {'end': 2575.003, 'text': "So I'm using couple of 1D arrays and again an n cross m loop.", 'start': 2570.142, 'duration': 4.861}, {'end': 2579.664, 'text': 'So guys, I hope you understood the recursion which we started off.', 'start': 2575.583, 'duration': 4.081}, {'end': 2581.464, 'text': 'The memoization you understood.', 'start': 2580.284, 'duration': 1.18}, {'end': 2584.585, 'text': "If you understood these two things, you're pretty much comfortable.", 'start': 2581.844, 'duration': 2.741}, {'end': 2589.59, 'text': 'and then, uh, we wrote the tabulation, then we did the space optimization.', 'start': 2585.485, 'duration': 4.105}, {'end': 2603.705, 'text': 'so, just in case you understood the whole package and and the entire dp on strings because this is where we wrap up on dp on strings and i hope i was able to explain you all the dp on string problems.', 'start': 2589.59, 'duration': 14.115}, {'end': 2611.516, 'text': "uh, not sure how, but let me know in the comment section if you're not comfortable enough with dp on strings and you can solve all the problems.", 'start': 2603.705, 'duration': 7.811}, {'end': 2615.698, 'text': 'so, guys, just in case you loved this video, please give it a thumbs up.', 'start': 2611.516, 'duration': 4.182}, {'end': 2618.799, 'text': "and if you're new to this channel, please, please, please do consider subscribing to us.", 'start': 2615.698, 'duration': 3.101}, {'end': 2620.86, 'text': "and yeah, with this i'll be wrapping up this video.", 'start': 2618.799, 'duration': 2.061}, {'end': 2621.64, 'text': "let's meet in the next one.", 'start': 2620.86, 'duration': 0.78}, {'end': 2622.581, 'text': 'till then, bye, bye, take care.', 'start': 2621.64, 'duration': 0.941}], 'summary': 'Explanation of recursion, memoization, tabulation, and space optimization for dynamic programming on strings.', 'duration': 70.689, 'max_score': 2551.892, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo2551892.jpg'}], 'start': 2308.376, 'title': 'Space optimization in programming and dynamic programming', 'summary': 'Covers the concept of space optimization in programming, emphasizing the dependency on previous elements and recommending self-practice. it also explains space optimization in dynamic programming, highlighting key steps and resulting in a 100% improvement in space efficiency through the use of 1d arrays and an n cross m loop.', 'chapters': [{'end': 2349.549, 'start': 2308.376, 'title': 'Space optimization in programming', 'summary': 'Explains the concept of space optimization in programming by emphasizing the dependency on previous elements and the need to declare base cases, recommending self-practice before explanation.', 'duration': 41.173, 'highlights': ['The need for space optimization arises due to dependencies on previous elements, making it possible to optimize the space usage.', 'The first problem faced in space optimization is the requirement to declare base cases, which can make the process tricky.', 'The chapter encourages self-practice before explanation, promoting understanding and proficiency in space optimization.']}, {'end': 2622.581, 'start': 2349.549, 'title': 'Space optimization in dynamic programming', 'summary': 'Explains the process of space optimization in dynamic programming, highlighting the key steps and recommending pen-and-paper analysis, emphasizing a step-by-step approach and the use of 1d arrays and an n cross m loop, resulting in a 100% improvement in space efficiency.', 'duration': 273.032, 'highlights': ['The process of space optimization involves step-by-step analysis and the utilization of 1D arrays and an n cross m loop, resulting in a 100% improvement in space efficiency.', 'The speaker recommends pen-and-paper analysis and emphasizes a step-by-step approach for space optimization, suggesting that this approach can lead to a 100% improvement in space efficiency.', 'The speaker emphasizes the importance of understanding recursion and memoization in dynamic programming, stating that proficiency in these two areas can lead to comfort with the subject.', 'The speaker concludes the discussion on dynamic programming by touching on the importance of understanding and solving problems related to dp on strings and encourages feedback on the topic.', 'The speaker encourages viewers to like and subscribe to the channel, concluding the video with a farewell message.']}], 'duration': 314.205, 'thumbnail': 'https://coursnap.oss-ap-southeast-1.aliyuncs.com/video-capture/ZmlQ3vgAOMo/pics/ZmlQ3vgAOMo2308376.jpg', 'highlights': ['The process of space optimization involves step-by-step analysis and the utilization of 1D arrays and an n cross m loop, resulting in a 100% improvement in space efficiency.', 'The need for space optimization arises due to dependencies on previous elements, making it possible to optimize the space usage.', 'The speaker emphasizes the importance of understanding recursion and memoization in dynamic programming, stating that proficiency in these two areas can lead to comfort with the subject.', 'The first problem faced in space optimization is the requirement to declare base cases, which can make the process tricky.', 'The chapter encourages self-practice before explanation, promoting understanding and proficiency in space optimization.', 'The speaker recommends pen-and-paper analysis and emphasizes a step-by-step approach for space optimization, suggesting that this approach can lead to a 100% improvement in space efficiency.', 'The speaker concludes the discussion on dynamic programming by touching on the importance of understanding and solving problems related to dp on strings and encourages feedback on the topic.', 'The speaker encourages viewers to like and subscribe to the channel, concluding the video with a farewell message.']}], 'highlights': ['The process of space optimization involves step-by-step analysis and the utilization of 1D arrays and an n cross m loop, resulting in a 100% improvement in space efficiency.', 'The chapter thoroughly explains the conversion of a dynamic programming problem into tabulation, providing detailed steps and code explanations. It also achieves a successful code submission and space optimization, ensuring a comprehensive understanding of the process.', 'Memoization reduces time complexity to O(n*m) and space complexity to n*m + n + m.', 'The solution transitions to dynamic programming, achieving a 100 score and optimizing the approach.', 'The process involves shrinking strings and solving smaller portions of the problem through recursion.', "The chapter explores scenarios of matching zero, one, or multiple characters with the star symbol, depicting the flexibility of matching any number of characters for the term, providing a comprehensive understanding of the star symbol's functionality.", "The '*' character can match any sequence of length 0 or more, allowing flexible pattern matching, as seen in the examples matching 'star' with 'c, d' and 'star star' with 'a, b, c, d'.", 'The problem involves matching strings containing question marks and stars, with the question mark representing a single character and the star representing a sequence of length 0 or more.', 'The process of using recursion to match patterns includes eliminating characters and analyzing base cases.', 'The example demonstrates how the question mark and the star in the strings S1 and S2 match with the corresponding characters in the other string.']}