[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];
        
    }
};