动态规划两个数组的dp问题系列一＞两个字符串的最小ASCII 删除和

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

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

        //统计元素和
        int sum = 0;
        for(char x : s1.toCharArray()) sum += x;
        for(char y : s2.toCharArray()) sum += y;

        return sum - dp[m][n] * 2;
    }
}