leetcode-----97. 交错字符串

• 链接：https://leetcode-cn.com/problems/interleaving-string/

代码

class Solution {
public:
    bool isInterleave(string s1, string s2, string s3) {
        int n = s1.size(), m = s2.size();
        if (m + n != s3.size()) return false;
        vector<vector<bool>> f(n + 1, vector<bool>(m + 1));
        s1 = ' ' + s1, s2 = ' ' + s2, s3 = ' ' + s3;

        for (int i = 0; i <= n; ++i) {
            for (int j = 0; j <= m; ++j) {
                if (!i && !j) f[i][j] = true;
                else {
                    if (i && s1[i] == s3[i + j]) f[i][j] = f[i - 1][j];
                    if (j && s2[j] == s3[i + j]) f[i][j] = f[i][j] || f[i][j - 1];
                }
            }
        }       
        return f[n][m];
    }
};