zoj2050_fipgame

 

     来源：http://acm.zju.edu.cn/onlinejudge/showProblem.do?problemId=1050

     

     本题用了深度优先，还是递归，耗时90MS，不是个好方法，比较好的应该是如

网上所说的用BFS，位运算，

 

      #include<iostream>#include<string.h>using namespace std;int N;int step;bool martic[5][5];int move[8]={0,1,0,-1,1,0,-1,0};bool full(){int x,y;bool mark=martic[1][1];for(int k=2;k<=16;k++){x=(k-1)/4+1;y=(k-1)%4+1;if(martic[x][y]!=mark)return false;}return true;}void bfs(int k,int fip){int x,y,a,b,i;if(full()){if(step>fip)step=fip;return;} if(k>16){return ;}else{x=(k-1)/4+1;y=(k-1)%4+1;bfs(k+1,fip);martic[x][y]=!martic[x][y];for( i=0;i<8;i=i+2){a=x+move[i];b=y+move[i+1];if(a>0 && b>0 &&a<5 && b<5)martic[a][b]=!martic[a][b];}bfs(k+1,fip+1);martic[x][y]=!martic[x][y];for( i=0;i<8;i=i+2){a=x+move[i];b=y+move[i+1];if(a>0 && b>0 &&a<5 && b<5)martic[a][b]=!martic[a][b];}}}int main(){int i,j;char ch;cin>>N;while(N--){step=100;for(i=1;i<=4;i++){for(j=1;j<=4;j++){cin>>ch;if(ch=='b')martic[i][j]=1;elsemartic[i][j]=0;}}bfs(1,0);if(step==100)cout<<"Impossible"<<endl;elsecout<<step<<endl;if(N)cout<<endl;}return 0;}