HDU1495 BFS

题意：三个瓶子，容量为s，n，m，且s装满饮料 s=m+n

求至少倒多少下能使得某两个瓶子装着相同多的饮料。

bfs 模拟

View Code 
  1 #include<stdio.h>
  2 #include<string.h>
  3 #include<math.h>
  4 #include<queue>
  5 #include<algorithm>
  6 using namespace std;
  7 const int maxn = 105;
  8 struct node{
  9     int s,n,m,t;
 10 };
 11 int s,n,m;
 12 int vis[ maxn ][ maxn ][ maxn ];
 13 
 14 int bfs(){
 15     node now,next;
 16     queue<node>q;
 17     while( !q.empty() )
 18         q.pop();
 19     now.s=s,now.n=now.m=now.t=0;
 20     memset( vis,0,sizeof( vis ));
 21     vis[s][0][0]=1;//vis[ now ]=1;
 22     q.push( now );
 23     while( !q.empty() ){
 24         now=q.front(),q.pop();
 25         if( ( now.s==now.n&&now.m==0 )||( now.s==now.m&&now.n==0 )||( now.m==now.n&&now.s==0 ) )
 26             return now.t;
 27         int tmp;
 28         if( now.s!=0 ){
 29             if( now.n!=n ){
 30                 tmp=min( now.s,n-now.n );
 31                 next=now;
 32                 next.t=now.t+1;
 33                 next.s-=tmp;
 34                 next.n+=tmp;
 35                 if( vis[next.s][next.n][next.m]==0/*vis[ next ]==0*/ ){
 36                     vis[next.s][next.n][next.m]=1;//vis[ next ]=1;
 37                     q.push( next );
 38                 }
 39             }
 40             if( now.m!=m ){
 41                 tmp=min( now.s,m-now.m );
 42                 next=now;
 43                 next.t=now.t+1;
 44                 next.s-=tmp;
 45                 next.m+=tmp;
 46                 if( vis[next.s][next.n][next.m]==0/*vis[ next ]==0*/ ){
 47                     vis[next.s][next.n][next.m]=1;//vis[ next ]=1;
 48                     q.push( next );
 49                 }
 50             }
 51         }// 1 to (2 or 3)
 52         if( now.n!=0 ){
 53             tmp=now.n;
 54             next=now;
 55             next.t=now.t+1;
 56             next.s+=tmp;
 57             next.n=0;
 58             if( vis[next.s][next.n][next.m]==0/*vis[ next ]==0*/ ){
 59                 vis[next.s][next.n][next.m]=1;//vis[ next ]=1;
 60                 q.push( next );
 61             }
 62             if( now.m!=m ){
 63                 tmp=min( m-now.m,now.n );
 64                 next=now;
 65                 next.t=now.t+1;
 66                 next.m+=tmp;
 67                 next.n-=tmp;
 68                 if( vis[next.s][next.n][next.m]==0/*vis[ next ]==0*/ ){
 69                     vis[next.s][next.n][next.m]=1;//vis[ next ]=1;
 70                     q.push( next );
 71                 }
 72             }
 73         }//2 to( 1 or 3 )
 74         if( now.m!=0 ){
 75             tmp=now.m;
 76             next=now;
 77             next.t=now.t+1;
 78             next.m=0;
 79             next.s+=tmp;
 80             if( vis[next.s][next.n][next.m]==0/*vis[ next ]==0*/ ){
 81                 vis[next.s][next.n][next.m]=1;//vis[ next ]=1;
 82                 q.push( next );
 83             }
 84             if( now.n!=n ){
 85                 tmp=min( n-now.n,now.m );
 86                 next=now;
 87                 next.t=now.t+1;
 88                 next.n+=tmp;
 89                 next.m-=tmp;
 90                 if( vis[next.s][next.n][next.m]==0/*vis[ next ]==0*/ ){
 91                     vis[next.s][next.n][next.m]=1;//vis[ next ]=1;
 92                     q.push( next );
 93                 }
 94             }
 95         }
 96     }
 97     return -1;
 98 }
 99 
100 int main(){
101     while( scanf("%d%d%d",&s,&n,&m),s+n+m ){
102         if( s%2==1 ){
103             printf("NO\n");
104             continue;
105         }
106         if( n==m ){
107             printf("1\n");
108             continue;
109         }
110         int ans=bfs();
111         if( ans!=-1 )
112             printf("%d\n",ans);
113         else
114             printf("NO\n");
115     }
116     return 0;
117 }

 

posted @ 2013-02-16 21:21  xxx0624  阅读(1411)  评论(0)  编辑  收藏  举报