POJ 1789 Truck History

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <cmath>
 5 #include <algorithm>
 6 #include <climits>
 7 #include <vector>
 8 #include <queue>
 9 #include <cstdlib>
10 #include <string>
11 #include <set>
12 #include <stack>
13 #define LL long long
14 #define pii pair<int,int>
15 #define INF 0x3f3f3f3f
16 using namespace std;
17 int n,mp[2010][2010],d[2010];
18 char s[2010][10];
19 bool done[2010];
20 priority_queue< pii,vector< pii >,greater< pii > >q;
21 int calc(int i,int j){
22     int tmp = 0;
23     for(int k = 0; k < 7; k++)
24         if(s[i][k] != s[j][k]) tmp++;
25     return tmp;
26 }
27 int prim(){
28     int ans = 0;
29     for(int i = 0; i <= n; i++){
30         done[i] = false;
31         d[i] = INF;
32     }
33     while(!q.empty()) q.pop();
34     d[1] = 0;
35     q.push(make_pair(d[1],1));
36     while(!q.empty()){
37         int u = q.top().second;
38         int w = q.top().first;
39         q.pop();
40         if(done[u]) continue;
41         done[u] = true;
42         ans += w;
43         for(int i = 1; i <= n; i++){
44             if(d[i] > mp[u][i]){
45                 d[i] = mp[u][i];
46                 q.push(make_pair(d[i],i));
47             }
48         }
49     }
50     return ans;
51 }
52 int main() {
53     int i,j;
54     while(scanf("%d",&n),n){
55         for(i = 0; i <= n; i++){
56             for(j = 0; j <= n; j++)
57                 mp[i][j] = INF;
58         }
59         for(i = 1; i <= n; i++)
60             scanf("%s",s[i]);
61         for(i = 1; i <= n; i++){
62             for(j = i+1; j <= n; j++)
63                 mp[i][j] = mp[j][i] = calc(i,j);
64         }
65         printf("The highest possible quality is 1/%d.\n",prim());
66     }
67     return 0;
68 }