HDU 1495 非常可乐 (kuangbin带你飞 专题一:简单搜索)

六种倒可乐情况...m到n或s，n倒m或s，s倒n或m...每一种倒法都有两种：倒满了或者没倒满...应该不算是难题，不过就是不好写...写的满令人崩溃的...去hdu交这个题目的时候发现以前A过了，看了一下好像是看的讨论版的规律...真是惭愧...

BFS写法：

#include<cstring>
#include<cstdlib>
#include<cmath>
#include<algorithm>
#include<queue>
#include<iostream>
using namespace std;
int used[105][105];//判断两个杯子装可乐的情况是否出现过
struct node
{
int m,n,s,t;
};
int m,n,s;
int bfs()
{
queue<node> q;
node  now,next;
now.m=now.n=now.t=0;
now.s=s;
q.push(now);
memset(used,0,sizeof(used));
used[0][0]=1;
while(!q.empty())
{
now=q.front();
q.pop();
if(now.n==now.s&&now.s==s/2)
return now.t;
if(now.m+now.s>m)  //s->m
{
next.m=m,next.n=now.n,next.s=now.m+now.s-m,next.t=now.t+1;
if(used[next.m][next.n]==0)
{
used[next.m][next.n]=1;
q.push(next);
}
}
else
{
next.m=now.m+now.s,next.n=now.n,next.s=0,next.t=now.t;
if(used[next.m][next.n]==0)
{
used[next.m][next.n]=1;
q.push(next);
}
}
if(now.n+now.s>n)  //s->n
{
next.m=now.m,next.n=n,next.s=now.n+now.s-n,next.t=now.t+1;
if(used[next.m][next.n]==0)
{
used[next.m][next.n]=1;
q.push(next);
}
}
else
{
next.m=now.m,next.n=now.n+now.s,next.s=0,next.t=now.t+1;
if(used[next.m][next.n]==0)
{
used[next.m][next.n]=1;
q.push(next);
}
}
if(now.m+now.n>n)  //m->n
{
next.m=now.m+now.n-n,next.n=n,next.s=now.s,next.t=now.t+1;
if(used[next.m][next.n]==0)
{
used[next.m][next.n]=1;
q.push(next);
}
}
else
{
next.m=0,next.n=now.n+now.m,next.s=now.s,next.t=now.t+1;
if(used[next.m][next.n]==0)
{
used[next.m][next.n]=1;
q.push(next);
}
}
if(now.m+now.s>s)  //m->s
{
next.m=now.m+now.s-s,next.n=now.n,next.s=s,next.t=now.t+1;
if(used[next.m][next.n]==0)
{
used[next.m][next.n]=1;
q.push(next);
}
}
else
{
next.m=0,next.n=now.n,next.s=now.m+now.s,next.t=now.t+1;
if(used[next.m][next.n]==0)
{
used[next.m][next.n]=1;
q.push(next);
}
}
if(now.n+now.m>m)  //n->m
{
next.m=m,next.n=now.n+now.m-m,next.s=now.s,next.t=now.t+1;
if(used[next.m][next.n]==0)
{
used[next.m][next.n]=1;
q.push(next);
}
}
else
{
next.m=now.n+now.m,next.n=0,next.s=now.s,next.t=now.t+1;
if(used[next.m][next.n]==0)
{
used[next.m][next.n]=1;
q.push(next);
}
}
if(now.n+now.s>s) //n->s
{
next.m=now.m,next.n=now.n+now.s-s,next.s=s,next.t=now.t+1;
if(used[next.m][next.n]==0)
{
used[next.m][next.n]=1;
q.push(next);
}
}
else
{
next.m=now.m,next.n=0,next.s=now.n+now.s,next.t=now.t+1;
if(used[next.m][next.n]==0)
{
used[next.m][next.n]=1;
q.push(next);
}
}
}
return -1;
}
int main()
{
while(cin>>s>>n>>m,n+m+s)
{
if(s%2)
printf("NO\n");
else
{
if(n<m) swap(n,m);
int ans=bfs();
if(ans==-1)
printf("NO\n");
else
printf("%d\n",ans);
}
}
return 0;
}

规律写法：

#include <cstdio>

int gcd(int x, int y)
{
return y ? gcd(y, x % y) : x;
}

int main()
{
int a, b, c;

while (scanf("%i%i%i", &a, &b, &c), a + b + c) {
(a /= gcd(b, c)) & 1 && ~puts("NO") || printf("%i\n", a - 1);
}
return 0;
}