Poj Solution 2088

http://poj.org/problem?id=2088

#include<iostream>
#include"algorithm"
using namespace std;

int dis[21][21];
int tim[21],n;
int id[21],mint[21];

int cmp(int a,int b)
{
    return mint[a]<mint[b];
}

void init()
{
    int i,j,k;
    for(i=0;i<n;i++)
    cin>>tim[i];
    
    for(i=0;i<n;i++)
    for(j=0;j<n;j++)
    {
        cin>>dis[i][j];
    }
    
    for(k=0;k<n;k++)
    for(i=0;i<n;i++)
    for(j=0;j<n;j++)
    if(dis[i][k]+dis[k][j]<dis[i][j])
    dis[i][j]=dis[i][k]+dis[k][j];
    
    for(i=0;i<n;i++)
    {
        mint[i]=9999;id[i]=i;
        for(j=0;j<n;j++)
        {
            dis[j][i]+=tim[i];
            if(dis[j][i]<mint[i])mint[i]=dis[j][i];
        }
    }
    std::sort(&id[0],&id[n],cmp);

}

long answer;
long visit;
int ll;
bool find(int a,int s,int rest)
{
    long k;int i,t,limit=5;
    
    if(s>answer)answer=s;
    
    if(answer==n)return 1;
    visit^=1<<a;

    t=0;
    for(i=0;t<=rest&&i<n;i++)
    if(!(visit&(1<<id[i])))
    {
        t+=mint[id[i]];
    }
    
    if(i+s<answer)return 0;

    for(i=0;i<n&&limit;i++)
    {
        if(!(visit&(1<<i))&&rest>=dis[a][i])
        {
            limit--;
            if(find(i,s+1,rest-dis[a][i]))return 1;
        }
    }
        
    visit^=1<<a;
    
    return 0;
}

int main()
{
    int i,t,c=1;

    while(1)
    {
        cin>>n;
        if(n==0)break;
        init();
        
        answer=0;
        for(i=0;i<n;i++)
        if(420>=tim[i])
        {
            visit=0;
            t=find(i,1,420-tim[i]);
        }
        
        cout<<answer<<endl;
    }
    return 0;
}