leetCode.97. 交错字符串

题目思路

代码

class Solution {
public:
    bool isInterleave(string s1, string s2, string s3) {
        int n = s1.size(), m = s2.size();
        if ( s3.size() != n + m ) 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];
    }
};