Kitchen Measurements UVALive - 7354

Posted 2020-10-06 MeowMeowMeow

https://wenku.baidu.com/view/9b4a1bd476a20029bd642dd4.html
//这道题学了很多东西- -
#include <iostream>
#include <algorithm>
#include <stdio.h>
#include <set>
#include <queue>
#include <cstring>
#include <string>
#include <limits.h>
#include <string.h>
#include <vector>
#include <map>
#define LL long long
#define INF 2100000000
#define fi first
#define se second
#define lowbit(x) (x&(-x))
#define eps 5e-7
using namespace std;
const int maxn=(int)5010;
const int maxm=(int)2510;
const LL MOD=(LL)1e9+7;
int n,meow;
int v[10];
int vis[61*65*65*65+3*65*65+10]; //标记这个的时候 设a[0]权值最小 a[4]权值最大 那么最大的数组为 0 0 3 61 0 只需要hash前4位 第5位因为总和一样所以是确定的 
//map TLE unordMAP 1500ms 数组 760ms

#define base 65
struct nod{
    int a[5];
    int val;
    nod(int b[5],int val=0):val(val){for(int i=0;i<n;i++)a[i]=b[i];}
    bool operator <(const nod&a)const{return val>a.val;}
    void copyy(int b[5]){for(int i=0;i<n;i++) b[i]=a[i];}
};
int gethash(int a[]){
    int s=0,b=1;
    for(int i=0;i<n-1;i++)s+=a[i]*b,b*=base;
    return s;
}
void out(int a[]){

    for(int i=0;i<n;i++)printf("%d ",a[i]);printf("\n");
}
int bfs(){
    int s[5]={0};
    priority_queue<nod> q;  //使用队列会导致遍历所有情况 取ans最小值 优先队列会快一些 
    s[0]=v[0];vis[gethash(s)]=-1;
    q.push(nod(s,0));
    while(!q.empty()){
        nod t=q.top();q.pop();
        if(t.a[0]==meow) return t.val;
        t.copyy(s);
       // out(s);
        for(int i=0;i<n;i++)
        for(int j=0;j<n;j++){
            if(i==j||!s[i]&&!s[j])continue;
            int w=min(s[i],v[j]-s[j]);
            s[i]-=w;s[j]+=w;
            int ha=gethash(s);
            if(!vis[ha]||vis[ha]&&vis[ha]>t.val+w){
                q.push(nod(s,t.val+w));
                vis[ha]=t.val+w;
            }
            s[i]+=w;s[j]-=w;
        }
    }
    return -1;
}
int main()
{
#ifdef shuaishuai
    freopen("C:\\Users\\hasee\\Desktop\\a.txt","r",stdin);
    //freopen("C:\\Users\\hasee\\Desktop\\b.txt","w",stdout);
#endif
    while(~scanf("%d",&n)){
        for(int i=0;i<n;i++)scanf("%d",v+i);
        scanf("%d",&meow);
        memset(vis,0,sizeof vis);
        int ans=bfs();
        if(ans!=-1)cout<<ans<<endl;
        else cout<<"impossible"<<endl;
    }
    return 0;
}