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()];
}
};