[LeetCode] Interleaving String

class Solution {public:    bool isInterleave(string s1, string s2, string s3) {        // Start typing your C/C++ solution below        // DO NOT write int main() function            int m = s1.size();        int n = s2.size();                if (m + n != s3.size()) return false;                vector<vector<int> > dp(m + 1, vector<int>(n + 1));                dp[0][0] = true;                for (int i = 1; i <= m; i++) {            dp[i][0] = dp[i - 1][0] && (s1[i - 1] == s3[i - 1]);        }                for (int j = 1; j <= n; j++) {            dp[0][j] = dp[0][j - 1] && (s2[j - 1] == s3[j - 1]);        }                for (int i = 1; i <= m; i++) {            for (int j = 1; j <= n; j++) {                dp[i][j] = dp[i - 1][j] && (s1[i - 1] == s3[i + j - 1]) ||                            dp[i][j - 1] && (s2[j - 1] == s3[i + j - 1]);            }        }                return dp[m][n];    }};

Small Case: 12ms

Large Case: 16ms

Time: O(n^2)

Space: O(n^2)