poj1789Truck History(简单最小生成树）

http://poj.org/problem?id=1789

模板题 题意是一个字符串跟一个字符不同的字符串有多少 这个数量就相当于权值 连起来最小

#include <iostream>
#include<algorithm>
#include<string.h>
#include<cstdio>
#define INF 0x3f3f3f3f
using namespace std;
char c[2001][10];
int w[2001][2001],vis[2001],low[2001],s;
void prime(int n)
{
    int i,j,k,m;
    memset(vis,0,sizeof(vis));
    vis[1] = 1;
    for(i =2 ; i <= n ; i++)
    low[i] = w[1][i];
    for(i = 1; i <= n ; i++)
    {
        m = INF;
        for(j = 1; j <= n ; j++)
        if(!vis[j]&&low[j]<m)
        m = low[k=j];
        if(m==INF)
        break;
        s+=m;
        vis[k] = 1;
        for(j = 1; j <= n ; j++)
        if(!vis[j]&&low[j]>w[k][j])
        low[j] = w[k][j];
    }
}
int main()
{
    int i,j,k,n,m,y,x;
    while(scanf("%d%*c",&n)&&n)
    {
        memset(w,INF,sizeof(w));
        s = 0;
        for(i = 1; i <= n ; i++)
        {
            gets(c[i]);
        }
        for(i = 1; i <= n ; i++)
        {
            for(j = i+1; j <= n ; j++)
            {
                y = 0;
                for(x = 0 ; x < 7 ; x++)
                if(c[j][x]!=c[i][x])
                y++;
                if(w[i][j]>y)
                {
                    w[i][j] = y;
                    w[j][i] = y;
                }
            }
        }
        prime(n);
        printf("The highest possible quality is 1/%d.\n",s);
    }
    return 0;
}