uva 321 - The New Villa bfs+递归

    利用二进制来表示房间灯的情况，再用独立参数表示现在所在房间，bfs完成查找，递归完成输出

    注意一下每组数据后要换行，不要忘了

/*
author:jxy
lang:C/C++
university:China,Xidian University
**If you need to reprint,please indicate the source**
*/
#include <cstdio>
#include <cstring>
#include <queue>
using namespace std;
int vis[11][2000];
int pre[11][2000];
int r,d,s;
struct node
{
    int step,now,state;
};
queue<node> q;
vector<int> sw[11];
vector<int> door[11];
node now,next;
bool input()
{
    scanf("%d%d%d",&r,&d,&s);
    if(r+d+s==0)return 0;
    int i,f,t;
    for(i=1;i<=r;i++)
    {
        sw[i].clear();
        door[i].clear();
    }
    for(i=0;i<d;i++)
    {
        scanf("%d%d",&f,&t);
        door[f].push_back(t);
        door[t].push_back(f);
    }
    for(i=0;i<s;i++)
    {
        scanf("%d%d",&f,&t);
        sw[f].push_back(t);
    }
    while(!q.empty())q.pop();
    memset(vis,0,sizeof(vis));
    i=1<<(r-1);//初始状态100000
    vis[1][i]=1;pre[1][i]=0;
    now.state=i;now.now=1;now.step=1;
    q.push(now);
    return 1;
}
void output(int Now,int state)//递归输出
{
    int ln,ls,nn=pre[Now][state];
    if(nn==0)return;
    ln=nn%100;
    ls=nn/100;
    output(ln,ls);
    if(ln!=Now)printf("- Move to room %d.\n",Now);
    else
    {
        int t=ls^state,i,flag;
        for(i=0;i<r&&!(t&1);i++,t>>=1);
        flag=ls&(1<<i);
        printf("- Switch %s light in room %d.\n",flag?"off":"on",r-i);
    }
}
void solve()
{
    int i,len,k,t,Now,nn;
    while(!q.empty()&&!vis[r][1])//末状态0000001
    {
        now=q.front();q.pop();
        Now=now.now;
        nn=now.state*100+Now;
        next.step=now.step+1;
        len=sw[Now].size();
        for(i=0;i<len;i++)//开关灯
        {
            k=sw[Now][i];
            if(k==Now)continue;//不能开关自己的灯
            t=now.state^(1<<(r-k));//异或改变这一位的值
            if(vis[Now][t])continue;
            vis[Now][t]=next.step;
            pre[Now][t]=nn;
            next.state=t;
            next.now=Now;
            q.push(next);
        }
        len=door[Now].size();
        for(i=0;i<len;i++)//走到有灯的房间
        {
            k=door[Now][i];
            if(((1<<(r-k))&now.state)==0||vis[k][now.state])continue;
            vis[k][now.state]=next.step;
            pre[k][now.state]=nn;
            next.state=now.state;
            next.now=k;
            q.push(next);
        }
    }
    if(vis[r][1])
    {
        printf("The problem can be solved in %d steps:\n",vis[r][1]-1);
        output(r,1);
    }
    else printf("The problem cannot be solved.\n");
}
int main()
{
    int T=0;
    while(input())
    {
        printf("Villa #%d\n",++T);
        solve();
        puts("");
    }
}