hdu1495（bfs）-白红宇

hdu1495（bfs）

阅读量：7059 次

发布时间：2019-06-28

本文共 2587 字，大约阅读时间需要 8 分钟。

题目链接：

题意：有三个杯子，开始时第一个杯子装满水（体积为a），倒来倒去，得到其中2个杯里的水的体积都为a/2，求最小次数，不存在就输出NO。

分析：因为被子没有刻度，所以倒入时要倒满或倒完才能保证知道容积，即有6种情况来分别遍历。

#include 
      
       #include 
       
        #include 
        
         #include 
         
          #include 
          
           #include 
           #include 
            
             #include 
             
              #define INF 100000000#define maxn 111111#define ll __int64#define lson 1,m,rt<<1#define rson m+1,r,rt<<1|1using namespace std;int vis[110][110][110];int a,b,c,flag;struct node{ int x,y,z; int step;};int judge(node k){ if((k.x==k.y&&k.z==0)||(k.x==k.z&&k.y==0)||(k.y==k.z&&k.x==0)) return 1; return 0;}void bfs(){ queue
              
               que; node now,next; int num; now.x=a;now.y=0; now.z=0;now.step=0; vis[a][0][0]=1; que.push(now); while(!que.empty()) { now=que.front();que.pop(); if(judge(now)) { printf("%d\n",now.step); flag=1; return; } if(now.x>0)//a倒入其他 { if(b>now.y)//a倒入b { num=b-now.y; next.z=now.z; next.step=now.step+1; if(now.x>num)//a倒不完 { next.x=now.x-num; next.y=b; } else//倒完 { next.y=now.x+now.y; next.x=0; } if(!vis[next.x][next.y][next.z]) { vis[next.x][next.y][next.z]=1; que.push(next); } } if(c>now.z)//a倒入c { num=c-now.z; next.y=now.y; next.step=now.step+1; if(now.x>num)//倒不完 { next.x=now.x-num; next.z=c; } else//倒完 { next.z=now.x+now.z; next.x=0; } if(!vis[next.x][next.y][next.z]) { vis[next.x][next.y][next.z]=1; que.push(next); } } } if(now.y>0)//b倒入其他 { if(a>now.x) { num=a-now.x; next.z=now.z; next.step=now.step+1; if(now.y>num) { next.y=now.y-num; next.x=a; } else { next.x=now.x+now.y; next.y=0; } if(!vis[next.x][next.y][next.z]) { vis[next.x][next.y][next.z]=1; que.push(next); } } if(c>now.z) { num=c-now.z; next.x=now.x; next.step=now.step+1; if(now.y>num) { next.y=now.y-num; next.z=c; } else { next.z=now.y+now.z; next.y=0; } if(!vis[next.x][next.y][next.z]) { vis[next.x][next.y][next.z]=1; que.push(next); } } } if(now.z>0)//c倒入其他 { if(b>now.y) { num=b-now.y; next.x=now.x; next.step=now.step+1; if(now.z>num) { next.z=now.z-num; next.y=b; } else { next.y=now.z+now.y; next.z=0; } if(!vis[next.x][next.y][next.z]) { vis[next.x][next.y][next.z]=1; que.push(next); } } if(a>now.x) { num=a-now.x; next.y=now.y; next.step=now.step+1; if(now.z>num) { next.z=now.z-num; next.x=a; } else { next.x=now.x+now.z; next.z=0; } if(!vis[next.x][next.y][next.z]) { vis[next.x][next.y][next.z]=1; que.push(next); } } } }}int main(){ while(scanf("%d%d%d",&a,&b,&c)>0) { if(a+b+c==0)break; if(a%2)//剪枝 { puts("NO"); continue; } memset(vis,0,sizeof(vis)); flag=0; bfs(); if(!flag)puts("NO"); }}