#include<iostream>
#include<cstdio>
using namespace std;
int d[1000000],w[1000000],p[1000000];
int main()
{
    int i,j,k=0,g=0,h=1;
    for(i=1;i<=4;i++){
        for(j=1;j<=4;j++)
        if (getchar()=='b') d[1]=(d[1]<<1)+1; else d[1]=d[1]<<1;
        getchar();
    }
    p[1]=0;
    while(g<h){
        g++;
        if(d[g]==0||d[g]==(1<<16)-1) {
            printf("%d",w[g]);
            k=1;
            break;
        }
        if (h>990000) continue;
        for(i=p[g]+1;i<=16;i++){
            h++;
            w[h]=w[g]+1;
            p[h]=i;
            d[h]=d[g]^(1<<(16-i));
            if(i-4>=1) d[h]^=1<<(16-i+4);
            if(i+4<=16) d[h]^=1<<(16-i-4);
            if(i%4!=0) d[h]^=1<<(16-i-1);
            if((i-1)%4!=0) d[h]^=1<<(16-i+1);
        }
    }
    if (!k) printf("Impossible");
    return 0;
}

• Re:16MS 位运算 代码短!!! (935) 03194766958 2014-07-19 17:33:34