Longest Common Subsequence

class Solution {
    static int lcs(String s1, String s2) {
        int n = s1.length();
        int m = s2.length();
        int[][] dp = new int[n + 1][m + 1];

        for (int i = 0; i <= n; i++) {
            for (int j = 0; j <= m; j++) {
                if (i == 0 || j == 0)
                    dp[i][j] = 0;
                else if (s1.charAt(i - 1) == s2.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[n][m];
    }
}