LeetCode - 1143. Longest Common Subsequence (Python)

Medium, DP - LCS

RunTime : 461 ms / Memory : 41.66 MB

문제
Given two strings text1 and text2, return the length of their longest common subsequence. If there is no common subsequence, return 0.

A subsequence of a string is a new string generated from the original string with some characters (can be none) deleted without changing the relative order of the remaining characters.

• For example, "ace" is a subsequence of "abcde".

A common subsequence of two strings is a subsequence that is common to both strings.

풀이

• 코테가 슬슬 돌아오는 시즌이라 다시금 풀어본 LCS
• LCS는 O(n * m)의 시간복잡도를 가진다.

class Solution:
    def longestCommonSubsequence(self, text1: str, text2: str) -> int:
        n = len(text1)
        m = len(text2)

        dp = [[0] * (m + 1) for _ in range(n + 1)]
        for i in range(1, n + 1):
            for j in range(1, m + 1):
                if text1[i - 1] == text2[j - 1]:
                    dp[i][j] = dp[i-1][j-1] + 1
                else:
                    dp[i][j] = max(dp[i-1][j], dp[i][j-1])
        
        return dp[n][m]