poj2965解题报告

这道题目与poj1753的解题思路非常相似。

区别在于翻转的时候方式稍微不一样，不过这不影响算法的中心思想。

#include<iostream>using namespace std;bool refrigerator[5][5] = {false};int step;bool flag = false;class node{public:int row;int col;};node steps[16+1];bool judge_all(){int i,j;for(i = 1;i<=4;i++)for(j = 1; j<=4;j++)if(refrigerator[i][j] == false)return false;return true;}void flip(int row,int col) {int i;for(i = 1;i<=4;i++){refrigerator[i][col] = !refrigerator[i][col];refrigerator[row][i] = !refrigerator[row][i];}refrigerator[row][col] = !refrigerator[row][col];}void dfs(int row,int col,int deep){if(step == deep){flag = judge_all();return;}if(row > 4 || flag ) return ;flip(row,col);// 将步伐记录在数组中steps[deep+1].row = row;steps[deep+1].col = col;if(col < 4)dfs(row,col+1,deep+1);else dfs(row+1,1,deep+1);flip(row,col);if(col< 4)dfs(row,col+1,deep);else dfs(row+1,1,deep);return;}int main(){int i,j;char temp;for(i = 1;i<=4;i++)for(j = 1; j<=4 ; j++){cin>>temp;if(temp == '-')refrigerator[i][j] = true;}for(step = 0; step <= 16 ; step ++){dfs(1,1,0);if(flag) break;}if(flag)cout<<step<<endl;else cout<<"Impossible"<<endl;for(int q = 1;q<=step;q++)cout<<steps[q].row<<" "<<steps[q].col<<endl;//system("pause");return 0;}