HDOJ1495(倒水BFS)

#include"cstdio"
#include"cstring"
#include"queue"
#include"algorithm"
using namespace std;
const int MAXN=105;
struct node{
    int s,n,m,step;
    node(int cs,int cn,int cm,int cstep):s(cs),n(cn),m(cm),step(cstep){}
    node(){}
};
int S,N,M;
int vis[MAXN][MAXN][MAXN];
bool judge(int s,int n,int m)
{
    if((s==n&&m==0)||(s==m&&n==0)||(n==m&&s==0))    return true;
    return false;
}
void bfs()
{
    memset(vis,0,sizeof(vis));
    queue<node> que;
    que.push(node(S,0,0,0));
    vis[S][0][0]=1;
    while(!que.empty())
    {
        node now = que.front();que.pop();
        if(judge(now.s,now.n,now.m))
        {
            printf("%d\n",now.step);
            return;
        }
        int ts,tn,tm;
        //S->N;
        ts=now.s-min(N-now.n,now.s);//不带刻度倒水经典公式 
        tn=now.n+min(N-now.n,now.s);
        tm=now.m;
        if(!vis[ts][tn][tm])
        {
            vis[ts][tn][tm]=1;
            que.push(node(ts,tn,tm,now.step+1));
        }
        //S->M;
        ts=now.s-min(M-now.m,now.s);
        tm=now.m+min(M-now.m,now.s);
        tn=now.n;
        if(!vis[ts][tn][tm])
        {
            vis[ts][tn][tm]=1;
            que.push(node(ts,tn,tm,now.step+1));
        }
        //N->S; S>=N
        ts=now.s+now.n;
        tn=0;
        tm=now.m;
        if(!vis[ts][tn][tm])
        {
            vis[ts][tn][tm]=1;
            que.push(node(ts,tn,tm,now.step+1));
        }
        //N->M
        ts=now.s;
        tn=now.n-min(M-now.m,now.n);
        tm=now.m+min(M-now.m,now.n);
        if(!vis[ts][tn][tm])
        {
            vis[ts][tn][tm]=1;
            que.push(node(ts,tn,tm,now.step+1));
        }
        
        //M->S;S>=M
        ts=now.s+now.m;
        tn=now.n;
        tm=0;
        if(!vis[ts][tn][tm])
        {
            vis[ts][tn][tm]=1;
            que.push(node(ts,tn,tm,now.step+1));
        }
        
        //M->N
        ts=now.s;
        tn=now.n+min(N-now.n,now.m);
        tm=now.m-min(N-now.n,now.m);
        if(!vis[ts][tn][tm])
        {
            vis[ts][tn][tm]=1;
            que.push(node(ts,tn,tm,now.step+1));
        }
        
    }
    printf("NO\n");
}
int main()
{
    while(scanf("%d%d%d",&S,&N,&M)&&S&&N&&M)
    {
        if(S%2)
        {
            printf("NO\n");
        }
        else bfs();
    }
    
    return 0;
}