Solution.cpp

#include <string>
#include <vector>
#include <iostream>
#include <sstream>
#include <algorithm>
#include <tuple>
#include <deque>
#include <unordered_map>
#include <cmath>
using namespace std;

class Solution {
public:
    bool isInterleave(string s1, string s2, string s3) {
        int l1 = s1.size(), l2 = s2.size(), l3 = s3.size();
        if (l1 + l2 != l3) return false;
        vector<vector<bool>> dp (l1 + 1, vector<bool> (l2 + 1, false));
        dp[0][0] = true;
        for (int j = 1; j <= l2; j ++)
            dp[0][j] = dp[0][j-1] and s3[j-1] == s2[j-1];
        for (int i = 1; i <= l1; i ++)
            dp[i][0] = dp[i-1][0] and s3[i-1] == s1[i-1];
        // init finish
        for (int i = 1; i <= l1; i ++) {
            for (int j = 1; j <= l2; j ++) {
                dp[i][j] = dp[i-1][j] and s1[i-1] == s3[i + j - 1] or
                            dp[i][j-1] and s2[j-1] == s3[i + j - 1];
            }
        }
        return dp[l1][l2];
    }
};

int main() {
    Solution a;
    return 0;
}