1143 Longest Common Subsequence

Code:

Python3

class Solution:
    def longestCommonSubsequence(self, text1: str, text2: str) -> int:
        ret = [[0 for _ in range(len(text2) + 1)] for _ in range(len(text1) + 1)]
 
        for i in range(len(text1)):
            for j in range(len(text2)):
                ret[i+1][j+1] =  ret[i][j] + 1 if text1[i] == text2[j] else max(ret[i+ 1][j], ret[i][j + 1])
 
        return ret[len(text1)][len(text2)]

Big O Analysis

• Runtime The runtime complexity here is $O(nm)$ where $n==len(text1)$ and $m==len(text2)$
• Memory The memory usage is $O(1)$ since we are not using any extra datastructure.

— A

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