poj 1789 每个字符串不同的字母数代表两个结点间的权值 （MST）

 1 # include <iostream>
 2 # include <cstdio>
 3 # include <cstring>
 4 # include <algorithm>
 5 # include <cmath>
 6 # define LL long long
 7 using namespace std ;
 8 
 9 const int INF=0x3f3f3f3f;
10 const int MAXN=2010;
11 bool vis[MAXN];
12 int lowc[MAXN];
13 int n ;
14 int cost[MAXN][MAXN] ;
15 char s[2010][10] ;
16 
17 int Prim()//点是0~n-1
18 {
19     int ans=0;
20     memset(vis,false,sizeof(vis));
21     vis[0]=true;
22     for(int i=1;i<n;i++)lowc[i]=cost[0][i];
23     for(int i=1;i<n;i++)
24     {
25         int minc=INF;
26         int p=-1;
27         for(int j=0;j<n;j++)
28             if(!vis[j]&&minc>lowc[j])
29             {
30                 minc=lowc[j];
31                 p=j;
32             }
33             if(minc==INF)return -1;//原图不连通
34             ans+=minc;
35             vis[p]=true;
36             for(int j=0;j<n;j++)
37                 if(!vis[j]&&lowc[j]>cost[p][j])
38                     lowc[j]=cost[p][j];
39     }
40     return ans;
41 }
42 
43 int main()
44 {
45 
46    // freopen("in.txt","r",stdin) ;
47     while(scanf("%d" , &n) !=EOF)
48     {
49         if (n == 0)
50             break ;
51         int w ;
52         int i , j ,k ;
53         for (i = 0 ; i < n ; i++)
54             for (j = 0 ; j < n ; j++)
55                cost[i][j] = INF ;
56         for (i = 0 ; i < n ; i++)
57             scanf("%s" , s[i]);
58         for (i = 0 ; i < n ; i++)
59             for (j = i+1 ; j < n ; j++)
60         {
61             w = 0 ;
62             for (k = 0 ; k < 7 ; k++)
63             {
64                 if (s[i][k] != s[j][k])
65                     w++ ;
66             }
67             cost[i][j] = w ;
68             cost[j][i] = w ;
69         }
70         printf("The highest possible quality is 1/%d.\n",Prim());
71 
72 
73     }
74     return 0 ;
75 }