POJ 1789 Truck History

#include<cstdio>
#include<cstring>
#include<string>
#include<queue>
#include<algorithm>
#include<queue>
#include<map>
#include<stack>
#include<iostream>
#include<list>
#include<set>
#include<cmath>
#define INF 0x7fffffff
#define eps 1e-6
using namespace std;
int n,m;
int fa[2001];
struct lx
{
int u,v,len;
}l[2000001];
int father(int x)
{
if(x!=fa[x])
fa[x]=father(fa[x]);
return fa[x];
}
bool cmp(lx a,lx b)
{
return a.len<b.len;
}
char str[2001][8];
int getlen(char *a,char *b)
{
int ans=0;
for(int i=0;i<7;i++)
if(a[i]!=b[i])ans++;
return ans;
}
int main()
{
while(scanf("%d",&n),n)
{
for(int i=1;i<=n;i++)
{
fa[i]=i;
scanf("%s",str[i]);
}
int cot=0;
for(int i=1;i<=n;i++)
{
for(int j=i+1;j<=n;j++)
{
l[cot].u=i;
l[cot].v=j;
l[cot++].len=getlen(str[i],str[j]);
}
}
sort(l,l+cot,cmp);
int ans=0;
for(int i=0;i<cot;i++)
{
int fu=father(l[i].u);
int fv=father(l[i].v);
if(fu==fv)continue;
fa[fv]=fu;
ans+=l[i].len;
}
printf("The highest possible quality is 1/%d.\n",ans);
}
}