LeetCode [1143] Longest Common Subsequence

1143. Longest Common Subsequence

Medium

Given two strings text1 and text2, return the length of their longest common subsequence.

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. (eg, "ace" is a subsequence of "abcde" while "aec" is not). A common subsequence of two strings is a subsequence that is common to both strings.

 

If there is no common subsequence, return 0.

 

Example 1:

Input: text1 = "abcde", text2 = "ace" 
Output: 3  
Explanation: The longest common subsequence is "ace" and its length is 3.

Example 2:

Input: text1 = "abc", text2 = "abc"
Output: 3
Explanation: The longest common subsequence is "abc" and its length is 3.

Example 3:

Input: text1 = "abc", text2 = "def"
Output: 0
Explanation: There is no such common subsequence, so the result is 0.

 

Constraints:

• 1 <= text1.length <= 1000
• 1 <= text2.length <= 1000
• The input strings consist of lowercase English characters only.

 

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class Solution { public int longestCommonSubsequence(String text1, String text2) { int m = text1.length(), n = text2.length(); int[][] dp = new int[m+1][n+1]; for(int i=1; i<=m; ++i){ for(int j=1; j<=n; ++j){ if(text1.charAt(i-1) == text2.charAt(j-1)){ dp[i][j] = dp[i-1][j-1]+1; }else{ dp[i][j] = Math.max(dp[i-1][j], dp[i][j-1]); } } } return dp[m][n]; } }