1143. Longest Common Subsequence
String, DP, AMateList ·Problem Statement
link: LeetCode.cn LeetCode 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.
Example:
Input: text1 = "abcde", text2 = "ace"
Output: 3
Input: text1 = "abc", text2 = "abc"
Output: 3
Input: text1 = "abc", text2 = "def"
Output: 0
Solution Approach
Algorithm
Implement
class Solution:
def longestCommonSubsequence(self, text1: str, text2: str) -> int:
#dp 0. 1. 2.
#dp[i][j] = dp[i - 1][j - 1] + 1 if v_i == v_j else max(dp[i - 1][j], dp[i][j - 1])
m, n = len(text1), len(text2)
dp = [[0] * (n + 1) for _ in range(m + 1)]
for i in range(1, m + 1):
for j in range(1, n + 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[i][j]