LeetCode 1143. Longest Common Subsequence

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

虽然不记得如何写的了 但是知道是DP 也知道应该用2D dp去记录
dp[i][j] represents for the LCS if text1 has a length of i and text2 has a length of j, the LCS of those two

then the coding part is really smooth.

class Solution {
    public int longestCommonSubsequence(String text1, String text2) {
        
        int m = text1.length();
        int 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];
    }
}