（广搜）可口可乐 -- hdu -- 1495

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#include <queue>

using namespace std;

#define maxn 110

struct node
{
    int a, b, c, step;
};

int S, N, M, vis[maxn][maxn][maxn];

int BFS()
{
    node p, q;
    p.a=S, p.b=0, p.c=0, p.step=0;

    memset(vis, 0, sizeof(vis));
    vis[S][0][0] = 1;

    queue<node>Q;
    Q.push(p);


    while(Q.size())
    {
        p = Q.front(), Q.pop();

        if((p.a==S/2&&p.b==S/2) || (p.b==S/2&&p.c==S/2) || (p.a==S/2&&p.c==S/2)) return p.step;

        for(int i=0; i<6; i++)
        {
            if(i==0) /// a->b
            {
                if(p.a+p.b>N)
                {
                    q.a = p.a+p.b-N;
                    q.b = N;
                }
                else
                {
                    q.a = 0;
                    q.b = p.a+p.b;
                }
                q.c = p.c;
            }
            else if(i==1) /// a->c
            {
                if(p.a+p.b>M)
                {
                    q.a = p.a+p.c-M;
                    q.c = M;
                }
                else
                {
                    q.a = 0;
                    q.c = p.a+p.c;
                }
                q.b = p.b;
            }
            else if(i==2) /// b->a
            {
                if(p.b+p.a>S)
                {
                    q.b = p.b+p.a-S;
                    q.a = S;
                }
                else
                {
                    q.b = 0;
                    q.a = p.b+p.a;
                }
                q.c = p.c;
            }
            else if(i==3)  /// b->c
            {
                if(p.b+p.c>M)
                {
                    q.b = p.b+p.c-M;
                    q.c = M;
                }
                else
                {
                    q.b = 0;
                    q.c = p.b+p.c;
                }
                q.a = p.a;
            }
            else if(i==4) /// c->a
            {
                if(p.c+p.a>S)
                {
                    q.c = p.c+p.a-S;
                    q.a = S;
                }
                else
                {
                    q.c = 0;
                    q.a = p.c+p.a;
                }
                q.b = p.b;
            }
            else if(i==5) ///  c->b
            {
                if(p.c+p.b>N)
                {
                    q.c = p.c+p.b-N;
                    q.b = N;
                }
                else
                {
                    q.c = 0;
                    q.b = p.c+p.b;
                }
                q.a = p.a;
            }
            q.step = p.step+1;
            if(!vis[q.a][q.b][q.c])
            {
                vis[q.a][q.b][q.c]=1;
                Q.push(q);
            }
        }
    }
    return -1;
}

int main()
{
    while(scanf("%d%d%d", &S, &N, &M), S+N+M)
    {
        if(S%2)
        {
            printf("NO\n");
            continue;
        }

        int ans = BFS();
        if(ans==-1)
           printf("NO\n");
        else
           printf("%d\n", ans);

    }
    return 0;
}