poj 1753

来源：互联网发布：邯郸seo 编辑：程序博客网时间：2024/05/09 04:21

每个位置翻转2次相当于没翻，另外每个位置翻转的时机不影响最终结果，所以枚举每个位置的状态翻还是没翻，一共2^16次递归

#include<iostream>#include <string> #include<vector>#include<algorithm>#include<set>#include<cmath>using namespace std;#define lch(i) ((i)<<1)#define rch(i) ((i)<<1|1)#define sqr(i) ((i)*(i))#define pii pair<int,int>#define mp make_pair#define FOR(i,b,e) for(int i=b;i<=e;i++)#define ms(a)memset(a,0,sizeof(a))const int maxnum = 10005;int mat[4][4];bool vis[4][4];int nxt[4][2]={{-1,0},{0,1},{1,0},{0,-1}};void flip(int x,int y){mat[x][y]=1-mat[x][y];FOR(i,0,3){if((x+nxt[i][0])>=0&&(x+nxt[i][0])<4&&(y+nxt[i][1])>=0&&(y+nxt[i][1])<4){mat[x+nxt[i][0]][y+nxt[i][1]]=1-mat[x+nxt[i][0]][y+nxt[i][1]];}}/*printf("\n");FOR(i,0,3){FOR(j,0,3){printf("%d",mat[i][j]);}printf("\n");}*/}bool check(){int sum=0;FOR(i,0,3){FOR(j,0,3){sum+=mat[i][j];}}if (sum==0||sum==16){return true;}return false;}int mintime=100;void enumM(int n,int times){if(n==16)return;enumM(n+1,times);flip(n/4,n%4);if(check()){mintime=min(mintime,times);}enumM(n+1,times+1);flip(n/4,n%4);}int main(){char ch;FOR(i,0,3){FOR(j,0,3){scanf("%c",&ch);if(ch=='w')mat[i][j]=0;elsemat[i][j]=1;}scanf("%c",&ch);}ms(vis);if(check()) printf("0\n");else{enumM(0,1);if(mintime>16)printf("Impossible\n");else printf("%d\n",mintime);}}

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