Longest Common Subsequence | (C++, Java, Python) |30 day Challenge | Day 26 | LeetCode

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LeetCode 30 day Challenge | Problem 26 | Longest Common Subsequence | 26 April,
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[@victorkash4718]

what a beautiful explanation sir, thank you making this video

[@KnowledgeCenter]

Glad to hear.

[@yangiiu4347]

Excellent video! It is a model for DP.

[@KnowledgeCenter]

Thanks.

[@williamwambua7710]

So this was a dynamic problem.

[@indranilthakur3605]

why do we keep all first row and column as 0 in the 2d array? The sole point of it to get the base case where none of it matches?

[@KnowledgeCenter]

First column means no character of text1 is selected. First row denotes no character of text2 is selected. You can get away with 1st row and column, and add a check in loop itself, if i == 0 or j == 0 then its 0.
If we don't select select any character from any of the texts then there cannot be any common subsequence, i.e., length of LCS will be 0.

[@indranilthakur3605]

@@KnowledgeCenter Also One thing I noticed, you created the 2D array of 7 rows and 6 columns[m+1][n+1] but created the matrix of 7 columns and 6 rows. t1 should be on y axis and t2 on x axis.

[@indranilthakur3605]

@@KnowledgeCenter thanks

[@KnowledgeCenter]

Correct observation. Technically switching text1 and text2 from row to column & vice versa doesn't make a difference in result. But, Yes, I should have maintained consistency. While explaining I should have put text 1 as rows and text2 as columns.