class Solution {
    public int longestCommonSubsequence(String text1, String text2) {
        if (text1.length() == 0 || text2.length() == 0) return 0;
        int len1 = text1.length();
        int len2 = text2.length();

        int[][] dp = new int[len1+1][len2+1];
        /**
         * if text1[i-1] = text2[j-1]：dp[i][j] = dp[i-1][j-1] + 1
         * if text1[i-1] != text2[j-1]： dp[i][j] = max(dp[i-1][j], dp[i][j-1])
         */

        for (int i = 0; i < dp.length; i++) dp[i][0] = 0;
        for (int j = 0; j < dp[0].length; j++) dp[0][j] = 0;

        for (int i = 1; i < dp.length; i++) {
            for (int j = 1; j < dp[0].length; 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[len1][len2];
    }
}

比较经典的二维dp题目，纪念一下