Leetcode: Interleaving String

Given s1, s2, s3, find whether s3 is formed by the interleaving ofs1 and s2.

For example,
Given:
s1 = "aabcc",
s2 = "dbbca",

When s3 = "aadbbcbcac", return true.
When s3 = "aadbbbaccc", return false.

public class Solution {    public boolean isInterleave(String s1, String s2, String s3) {// Start typing your Java solution below// DO NOT write main() functionint n1 = s1.length();int n2 = s2.length();int n3 = s3.length();if(n1 + n2 != n3)return false;boolean[][] ans = new boolean[n1 + 1][n2 + 1];// ans[i][j] == true means s3.substring(0, i + j) is an interleaving stringans[0][0] = true;for(int i = 1; i <= n1; i++){if(s1.charAt(i - 1) == s3.charAt(i - 1))ans[i][0] = true;elsebreak;}for(int i = 1; i <= n2; i++){if(s2.charAt(i - 1) == s3.charAt(i - 1))ans[0][i] = true;elsebreak;}for(int i = 1; i <= n1; i++){for(int j = 1; j <= n2; j++){if(s1.charAt(i - 1) == s3.charAt(i + j - 1))ans[i][j] = ans[i][j] || ans[i - 1][j];if(s2.charAt(j - 1) == s3.charAt(i + j - 1))ans[i][j] = ans[i][j] || ans[i][j - 1];}}return ans[n1][n2];}}