1143.longest-common-subsequence.java

/*
 * @lc app=leetcode id=1143 lang=java
 *
 * [1143] Longest Common Subsequence
 */

// @lc code=start

class Solution {
    public int longestCommonSubsequence(String text1, String text2) {
        // DP[i][j] represents the longest common subsequence
        // of text1[0 ... i] & text2[0 ... j].
        // DP[i][0]=DP[0][j]=0, since the empty string have 0 common subsequence.
        int len1 = text1.length(), len2 = text2.length();
        int[][] dp = new int[len1 + 1][len2 + 1];

        for (int i = 0; i < len1; i++) {
            for (int j = 0; j < len2; j++) {
                if (text1.charAt(i) == text2.charAt(j)) {
                    dp[i + 1][j + 1] = dp[i][j] + 1;
                } else {
                    dp[i + 1][j + 1] = Math.max(dp[i][j + 1], dp[i + 1][j]);
                }

            }
        }

        return dp[len1][len2];
    }
}

// @lc code=end