leetcode+ s3是否是由s1和s2构成，Dp

点击打开链接

//Dp
class Solution {
public:
    bool isInterleave(string s1, string s2, string s3) {
        int len1 = s1.size(), len2 = s2.size();
        if(s3.size() != len1+len2) return false;
        vector> f(len1+1, vector(len2+1, true));
        for(int i=1; i<=len1; i++){
            f[i][0] = (s1[i-1]==s3[i-1])&&f[i-1][0];
        }
        for(int j=1;j<=len2; j++){
            f[0][j] = (s2[j-1]==s3[j-1])&&f[0][j-1];
        }
        for(int i=1; i<=len1; i++){
            for(int j=1; j<=len2; j++){
                f[i][j] = ((s1[i-1]==s3[i+j-1])&&f[i-1][j]) ||((s2[j-1]==s3[i+j-1])&&f[i][j-1]);
            }
        }
        return f[len1][len2];
    }
};