HDU 1495 非常可乐 BFS

题目大意：中文题不说了。

题目思路：我有同学用GCD数论写出来的代码很简洁，但是很抱歉，数论蒟蒻，我觉得比赛的时候我没办法推出。如果用BFS的话思路很简单的，就是6方向广搜，只不过稍微麻烦点。具体看代码吧。

#include<cstdio>
#include<cstring>
#include<cmath>
#include<queue>
#include<algorithm>
#include<iostream>
#define MAX 115
using namespace std;

int vis[MAX][MAX][MAX],a,b,c,k;

bool check(int s,int n,int m)
{
    if(!vis[s][n][m] && s<=c && n<=a && m<=b && s>=0 && n>=0 && m>=0)
        return true;
    return false;
}

struct node
{
    int s,n,m,step;
};

int BFS()
{
    node now,next;
    now.s=c;
    now.n=0;
    now.m=0;
    now.step=0;
    queue<node>Q;
    Q.push(now);
    vis[c][0][0]=1;
    while(!Q.empty())
    {
        now=Q.front();
        Q.pop();
        if(now.s==k && now.m==k)
        {
            return now.step;
        }
        for(int i=0;i<6;i++)
        {
            if(i==0)//s->n
            {
                if(now.s==0)
                    continue;
                if(now.s >= (a-now.n))
                {
                    next.s=now.s-(a-now.n);
                    next.n=a;
                }

                else
                {
                    next.s=0;
                    next.n=now.n+now.s;
                }
                next.m=now.m;
            }

            else if(i==1)//n->m
            {
                if(now.n==0)
                    continue;
                if(now.n >= (b-now.m))
                {
                    next.n=now.n-(b-now.m);
                    next.m=b;
                }

                else
                {
                    next.n=0;
                    next.m=now.m+now.n;
                }
                next.s=now.s;
            }

            else if(i==2)//m->n
            {
                if(now.m==0)
                    continue;
                if(now.m >= (a-now.n))
                {
                    next.m=now.m-(a-now.n);
                    next.n=a;
                }

                else
                {
                    next.m=0;
                    next.n=now.n+now.m;
                }
                next.s=now.s;
            }

            else if(i==3)//s->m
            {
                if(now.s==0)
                    continue;
                if(now.s >= (b-now.m))
                {
                    next.s=now.s-(b-now.m);
                    next.m=b;
                }

                else
                {
                    next.s=0;
                    next.m=now.m+now.s;
                }
                next.n=now.n;
            }

            else if(i==4)//n->s
            {
                if(now.n==0)
                    continue;
                if(now.n >= (c-now.s))
                {
                    next.n=now.n-(c-now.s);
                    next.s=c;
                }

                else
                {
                    next.n=0;
                    next.s=now.s+now.n;
                }
                next.m=now.m;
            }

            else if(i==5)//m->s
            {
                if(now.m==0)
                    continue;
                if(now.m >= (c-now.s))
                {
                    next.m=now.m-(c-now.s);
                    next.s=c;
                }

                else
                {
                    next.m=0;
                    next.s=now.s+now.m;
                }
                next.n=now.n;
            }

            if(check(next.s,next.n,next.m))
            {
                vis[next.s][next.n][next.m]=1;
                next.step=now.step+1;
                Q.push(next);
            }
        }
    }
    return -1;
}

int main()
{
    while(scanf("%d%d%d",&c,&a,&b),a+b+c)
    {
        if(a > b)
            swap(a,b);
        if(c%2!=0)
        {
            printf("NO
");
            continue;
        }

        else
        {
            k=c/2;
            memset(vis,0,sizeof(vis));
            int ans=BFS();
            if(ans==-1)
                printf("NO
");
            else
                printf("%d
",ans);
        }
    }
    return 0;
}