POJ2965(TLE,Why?)

#include <stdafx.h>
#include <iostream>
#define MAX_STATE 65535
#define ALL_BLACK 65535
#define ALL_WHITE 0
#define WIDTH 4
#define HEIGTH 4
#define SIZE_OF_BOARD WIDTH*HEIGTH
#include <queue>

using namespace std;

int flip(int current,int pos){
    int row = (pos/WIDTH)*WIDTH;
    int b = current;
    current ^=1<<(row );
    current ^=1<<(row + 1);
    current ^=1<<(row + 2);
    current ^=1<<(row + 3);
    int col = pos%4;
    current ^=1<<(col);
    current ^=1<<(col+4);
    current ^=1<<(col+8);
    current ^=1<<(col+12);
    current ^=1<<pos;
    return current;
}

int main(int argc, char* argv[])
{
    //freopen("d:/t.txt","r",stdin);
    int step[MAX_STATE];
    int pre[MAX_STATE];
    int pos[MAX_STATE];
    int current_state = 0,next_state;
    char c;
    for(int i=0;i<SIZE_OF_BOARD;i++)
    {
        cin>>c;
        current_state += (c=='+')<<(i);
    }
    if(current_state==ALL_WHITE){
        printf("0\n");
        return 0;
    }
    memset(step,-1,sizeof(step));
    queue<int> q;
    q.push(current_state);
    step[current_state]=0;
    pre[current_state]=-1;
    while(!q.empty()){
        current_state = q.front();
        q.pop();
        for(int i=0;i<SIZE_OF_BOARD;i++)
        {
            next_state = flip(current_state,i);
            if(next_state==ALL_WHITE){
                pre[next_state] = current_state;
                pos[next_state] = i;
                int count = step[current_state]+1;
                int ans[16];
                printf("%d\n",count);
                for(int c = count-2;c>=0;c--)
                {
                    ans[c]=pos[pre[next_state]];
                    next_state = pre[next_state];
                }
                ans[count-1]=i;
                for(int i=0;i<count;i++)
                    printf("%d %d\n",ans[i]/4+1,ans[i]%4+1);
                return 0;
            }
            if(-1==step[next_state]){
                pre[next_state] = current_state;
                pos[next_state] = i;
                step[next_state] = step[current_state]+1;
                q.push(next_state);
            }
        }
    }
    printf("Impossible\n");
    return 0;
}