LeetCode OJ Interleaving String

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

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

When s3 = "aadbbcbcac", return true.

When s3 = "aadbbbaccc", return false.

class Solution {public:bool isInterleave(string s1, string s2, string s3) {if (s1.size() + s2.size() != s3.size()) return false;vector<vector<bool> > dp(s1.size() + 1);for (int i = 0; i < s1.size() + 1; i++) dp[i].resize(s2.size() + 1);dp[0][0] = true;for (int i = 1; i <= s2.size(); i++) {if (dp[0][i - 1] && s2[i - 1] == s3[i - 1]) dp[0][i] = true;}for (int i = 1; i <= s1.size(); i++) {if (dp[i - 1][0] && s1[i - 1] == s3[i - 1]) dp[i][0] = true;}for (int i = 1; i <= s1.size(); i++) {for (int j = 1; j <= s2.size(); j++) {if ((dp[i - 1][j] && s1[i - 1] == s3[i + j - 1]) || (dp[i][j - 1] && s2[j - 1] == s3[i + j - 1])) dp[i][j] = true;}}return dp[s1.size()][s2.size()];}};