这道题java用动规做超时了，改成c++爆内存，是二维数组的问题吗

import java.io.*;
import java.util.Scanner;

public class AC1 {
        public static void main(String[] args) throws Exception {
            BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
            Scanner scanner = new Scanner(System.in);

            int len = scanner.nextInt();
            char[] s1 = in.readLine().trim().toCharArray();
            char[] s2 = in.readLine().trim().toCharArray();
            int[][] dp = new int[len+1][];
            for (int i = 0; i < dp.length; i++) {
                dp[i] = new int[len+1];
            }

            for (int i = 1; i <= len; i++) {
                for (int j = 1; j <= len; j++) {
                    if (s1[i-1] == s2[j-1]) {
                        dp[i][j] = dp[i-1][j-1];
                    } else {
                        dp[i][j] = Math.min(dp[i-1][j-1], Math.min(dp[i-1][j], dp[i][j-1])) + 1;
                    }
                }
            }
            System.out.println(dp[len][len]);
        }

}