[leetcode]Scramble String

3D dp问题

 

class Solution {

public:

    bool isScramble(string s1, string s2) {

        // Start typing your C/C++ solution below

        // DO NOT write int main() function

        int N = s1.size();

        if(N != s2.size()) return false;

        if(N == 0) return s1 == s2;

            

        vector<vector<vector<bool>>> f(N, vector<vector<bool>>(N, vector<bool>(N+1, false)));

        

        for(int i = 0; i < N; i++){

            for(int j = 0; j < N; j++){

                f[i][j][1] = (s1[i] == s2[j]);

            }

        }



        bool tmp;

        

        for(int len = 2; len <= N; len++){

            for(int i = 0; i < N; i++){

                for(int j = 0; j < N; j++){

                    for(int k = 1; k < len; k++){

                        if(i+k >= N || j+k >= N || j+len-k >= N) continue;

                        

                        tmp = f[i][j][k] && f[i+k][j+k][len-k] || f[i][j+len-k][k] && f[i+k][j][len-k];

                        if(tmp){

                            f[i][j][len] = true;

                            break;

                        }   

                    }

                }

            }

        }

        

        return f[0][0][N];

        

    }

};