poj 2485 Highways

#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
using namespace std;

const int maxn=505;
struct Edge
{
int from,to,w;
} edge[250000+10];
int n,ans;
int G[maxn][maxn];
int Father[maxn];
bool cmp(const Edge&a,const Edge&b)
{
return a.w<b.w;
}
int Find(int x)
{
if(x!=Father[x]) return Father[x]=Find(Father[x]);
return Father[x];
}

int main()
{
int T,j,i;
scanf("%d",&T);
while(T--)
{
scanf("%d",&n);

for(i=0; i<=n; i++) Father[i]=i;
int tot=0;

for(i=1; i<=n; i++)
for(j=1; j<=n; j++)
scanf("%d",&G[i][j]);

for(i=1; i<=n; i++)
for(j=1; j<=n; j++)
if(G[i][j]!=0)
{
edge[tot].from=i;
edge[tot].to=j;
edge[tot].w=G[i][j];
tot++;
}

sort(edge,edge+tot,cmp);

for(i=0; i<tot; i++)
{
int u=edge[i].from;
int v=edge[i].to;
u=Find(u);
v=Find(v);
if(u!=v)
{
Father[u]=v;
ans=edge[i].w;
}
}
printf("%d\n",ans);
}
return 0;
}