hdoj1495简单BFS

#include <stdio.h>
#include <string.h>
#include <math.h>
#include <algorithm>
#include <iostream>
using namespace std;
#define LL __int64
#define mod 9973
#define N 100010

int n,m,s;

bool vis[102][110][110];
struct asd{
    int cup1;
    int cup2;
    int cup3;
    int step;
};
asd q[N];
int head,tail;

void bfs()
{
    memset(vis,0,sizeof(vis));

    head=0;tail=1;
    q[head].cup1=s;
    q[head].cup2=0;
    q[head].cup3=0;
    q[head].step=0;
    vis[s][0][0]=1;

    int x,y,z;
    while(head<tail)
    {
        int a=q[head].cup1;
        int b=q[head].cup2;
        int c=q[head].cup3;

        if(a==b&&a==s/2)
        {
            printf("%d\n",q[head].step);
            return;
        }
        //cup1->cup2|cup1->cup3|先cup1->cup2后cup1->cup3
        if(a>0)
        {
            //cup1->cup2只能倒满，或者倒不满
           //不会出现倒不满的现象，只会倒不倒；
            x=a-(n-b);
            y=n;
            z=c;
            if(!vis[x][y][z])
            {
                vis[x][y][z]=1;
                q[tail].cup1=x;
                q[tail].cup2=y;
                q[tail].cup3=z;
                q[tail].step=q[head].step+1;
                tail++;
            }
            x=0;
            y=n;
            z=m;
            if(!vis[x][y][z])
            {
                vis[x][y][z]=1;
                q[tail].cup1=x;
                q[tail].cup2=y;
                q[tail].cup3=z;
                q[tail].step=q[head].step+1;
                tail++;
            }
            x=(a-(m-c));
            y=b;
            z=m;
            if(!vis[x][y][z])
            {
                vis[x][y][z]=1;
                q[tail].cup1=x;
                q[tail].cup2=y;
                q[tail].cup3=z;
                q[tail].step=q[head].step+1;
                tail++;
            }
        }
        //cup2->cup1|cup2->cup3|\cup2->cup1;
        if(b>0)
        {
            x=a+b;
            y=0;
            z=c;
            if(!vis[x][y][z])
            {
                vis[x][y][z]=1;
                q[tail].cup1=x;
                q[tail].cup2=y;
                q[tail].cup3=z;
                q[tail].step=q[head].step+1;
                tail++;
            }
            if(b+c>=m)
            {
                x=a;
                y=b-(m-c);
                z=m;
                if(!vis[x][y][z])
                {
                    vis[x][y][z]=1;
                    q[tail].cup1=x;
                    q[tail].cup2=y;
                    q[tail].cup3=z;
                    q[tail].step=q[head].step+1;
                    tail++;
                }
                x=s-m;
                y=0;
                z=m;
                if(!vis[x][y][z])
                {
                    vis[x][y][z]=1;
                    q[tail].cup1=x;
                    q[tail].cup2=y;
                    q[tail].cup3=z;
                    q[tail].step=q[head].step+1;
                    tail++;
                }
            }
            else
            {
                x=a;
                y=0;
                z=b+c;
                if(!vis[x][y][z])
                {
                    vis[x][y][z]=1;
                    q[tail].cup1=x;
                    q[tail].cup2=y;
                    q[tail].cup3=z;
                    q[tail].step=q[head].step+1;
                    tail++;
                }
            }
        }
        //cup3->cup1|cup3->cup2\\cup3->cup1
        if(c>0)
        {
            x=a+c;
            y=b;
            z=0;
            if(!vis[x][y][z])
            {
                vis[x][y][z]=1;
                q[tail].cup1=x;
                q[tail].cup2=y;
                q[tail].cup3=z;
                q[tail].step=q[head].step+1;
                tail++;
            }
            if(b+c>=n)
            {
                x=a;
                y=n;
                z=c-(n-b);
                if(!vis[x][y][z])
                {
                    vis[x][y][z]=1;
                    q[tail].cup1=x;
                    q[tail].cup2=y;
                    q[tail].cup3=z;
                    q[tail].step=q[head].step+1;
                    tail++;
                }
                x=s-n;
                y=n;
                z=0;
                if(!vis[x][y][z])
                {
                    vis[x][y][z]=1;
                    q[tail].cup1=x;
                    q[tail].cup2=y;
                    q[tail].cup3=z;
                    q[tail].step=q[head].step+1;
                    tail++;
                }
            }
            else
            {
                x=a;
                y=b+c;
                z=0;
                if(!vis[x][y][z])
                {
                    vis[x][y][z]=1;
                    q[tail].cup1=x;
                    q[tail].cup2=y;
                    q[tail].cup3=z;
                    q[tail].step=q[head].step+1;
                    tail++;
                }
            }
        }
        head++;
    }
    printf("NO\n");
}

int main()
{
    while(~scanf("%d%d%d",&s,&n,&m))
    {
        if(s==0&&n==0&&m==0)
            break;
        if(n<m)
        {
            int temp=n;
            n=m;
            m=temp;
        }
        if(n+m<s||n+m>s||s%2==1)
        {
            puts("NO");
            continue;
        }
        bfs();
    }
    return 0;
}