#include <iostream>
  using namespace std;
  
 int step[65535]={0};  //记录步骤
 bool flag[65535]={false};  //防止重复搜索
 
 unsigned short qState[65535]; //搜索的状态，正好可以用一个16位的无符号短整形表示
 int rear = 0; //队列尾指针
 int top = 0; //队列头指针
 
 ///初始化：读入棋盘初始状态并把它转化为整数存入队列头，黑的位为1白的为0
 void Init()
 {
     unsigned short temp = 0;
     char c;
 
     for(int i=0; i < 4; i++)
         for(int j = 0; j < 4; j++)
         {    
             cin>>c;
             if('b' == c)
                 temp |= (1<<(i*4+j));
         }
 
     qState[rear++] = temp;
     flag[temp]  = true;
 }
 
 ///翻转一个棋子并按规则对齐周围棋子附加影响
 unsigned short move(unsigned short state, int i)
 {
     unsigned short temp=0; 
     temp |= (1<<i);
     if((i+1)%4 != 0) //右，且不在最右边
         temp |= (1<<(i+1));
     if(i%4 != 0) //左，且不在最左边
         temp |= (1<<(i-1));
     if(i+4 < 16) //下
         temp |= (1<<(i+4));
     if(i-4 >= 0) //上
         temp |= (1<<(i-4));
 
     return (state ^ temp);
 }
 
 //广度优先搜索，从队列中循环取出状态，并把翻转16次（即所有情况），一旦发现满足要求的立即停止，否则加入队列
 bool BFS()
 {
     while(rear > top)
     {
         unsigned short state = qState[top++];
         //qState.pop();
         if(0 == state || 65535 == state)
             {
                 cout<<step[state];
                 return true;
             }
        
         unsigned short temp=0;
         for (int i=0;i<16;i++){        	 	 
         	 temp = move(state,i);
         	 if(!flag[temp]){
         	 	 	qState[rear++] = temp;
                 	flag[temp] = true;
                 	step[temp] = step[state]+1;
         	 }
         }
         
         
     }    
 
     return false;
 }
 
 int main(void)
 {
     Init();
     if(!BFS()) cout<<"Impossible";

 }


就是step那个数组用来记录步数的。
int step[65535]={0};就WA
int step[65535] 就AC。。。
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