NYOJ(21)，BFS，三个水杯

题目链接：http://acm.nyist.net/JudgeOnline/problem.php?pid=21

BFS判环，vis标记状态即可。

#include <stdio.h>
#include <queue>
#include <string.h>

using namespace std;

bool vis[][][];

struct Cup
{
    int v[];
    int step;
};

int s[],t[];

int bfs()
{
    memset(vis,false,sizeof(vis));
    Cup start;
    start.step = ;
    start.v[] = s[];
    start.v[] = ;
    start.v[] = ;
    vis[s[]][][] = true;
    queue<Cup> Q;
    Q.push(start);
    while(!Q.empty())
    {
        start = Q.front();
        Q.pop();
        if(start.v[]==t[]&&start.v[]==t[]&&start.v[]==t[])
            return start.step;

        for(int i=; i<; i++)
        {
            for(int j=; j<; j++)
            {
                Cup tmp = start;
                if(i==j||tmp.v[i]==||tmp.v[j]==s[j])
                    continue;

                if(tmp.v[i]+tmp.v[j]<=s[j])
                {
                    tmp.v[j] = tmp.v[i]+tmp.v[j];
                    tmp.v[i] = ;
                }
                else
                {
                    tmp.v[i] = tmp.v[i] - (s[j]-tmp.v[j]);
                    tmp.v[j] = s[j];
                }
                tmp.step++;
                if(!vis[tmp.v[]][tmp.v[]][tmp.v[]])
                {
                    Q.push(tmp);
                    vis[tmp.v[]][tmp.v[]][tmp.v[]] = true;
                }
            }
        }
    }
    return -;
}

int main()
{
    int cases;
    scanf("%d",&cases);
    while(cases--)
    {
        for(int i=; i<; i++)
            scanf("%d",&s[i]);
        for(int i=; i<; i++)
            scanf("%d",&t[i]);
        printf("%d\n",bfs());
    }
    return ;
}