（2）POJ - 2965 The Pilots Brothers' refrigerator

对（1）的拓展，加个结构体保存路径

https://blog.csdn.net/qq_37591656/article/details/80014307

poj炸了不知道能否AC

#include <algorithm>
#include <cstdio>
#include <vector>
#include <queue>
#include <iostream>

using namespace std;
typedef long long int ll;

const int maxn=(1<<16)-1;
const int inf=0x3f3f3f3f;

queue<int> que;
int vis[maxn+10];
int step;

int endk;

struct Father{
    int lastState;
    int p;
}father[maxn+10];

int change(unsigned int x,int i,int j)
{
    int k;
    k=(1<<(i*4+j));
    x^=k;
    int t = i-1;
    while(t>=0)
    {
        k=(1<<(4*t--+j));
        x^=k;

    }
    t = i+1;
    while(t<4)
    {
        k=(1<<(4*(t++)+j));
        x^=k;
    }
    t = j+1;
    while(t<4)
    {
        k=(1<<(4*i+t++));
        x^=k;
    }
    t = j-1;
    while(t>=0)
    {
        k=(1<<(4*i+t--));
        x^=k;
    }
    return x;
}

int bfs(int state)
{
    step=0;
    while(!que.empty())
        que.pop();
    que.push(state);
    while(!que.empty())
    {
        int t=que.size();
        for(int i=0; i<t; i++)
        {
            int k=que.front();
            que.pop();
            if(k==0||k==maxn||step>16)
            {
                endk = k;
                return step;
            }
            for(int p=0; p<4; p++)
                for(int q=0; q<4; q++)
                {
                    int w;
                    w=change(k,p,q);
                    if(!vis[w])
                    {
                        que.push(w);
                        father[w].p = p*4+q;
                        father[w].lastState = k;
                    }
                    vis[w]=1;
                }
        }
        step++;
    }
}

int main()
{
    int state=0;
    char s[10];
    int k=0;
    for(int i=0; i<4; i++)
    {
        scanf("%s",s);
        for(int j=0; j<4; j++)
        {
            if(s[j]=='-')
                state+=(1<<k);
            k++;
        }
    }
    father[state].p = -1;

    int ans=bfs(state);
    printf("%d\n",ans);

    while(endk != state)
    {
        int t = father[endk].p;
        cout<<t/4 +1  <<' '<<t%4 +1<<endl;
        endk = father[endk].lastState;
    }

    return 0;
}