HDU-1233(还是通畅工程) Kruskal

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#define m n*(n-1)/2
using namespace std;

const int maxn = 205;

struct Edge{
int from, to;
int value;
}edges[maxn*(maxn-1)];

int UF[maxn];
int n;

bool cmp(Edge e1, Edge e2)
{
return e1.value < e2.value;
}
int find(int t)
{
return t == UF[t] ? t : find(UF[t]);
}

int Union(int a, int b, int ans, int idx)
{
int x = find(a);
int y = find(b);

if(x != y){
UF[y] = x;
ans += edges[idx].value;
}
return ans;
}

void readin()
{
for(int i = 0; i < m; ++i)
{
scanf("%d%d%d", &edges[i].from, &edges[i].to, &edges[i].value);
}
}

void init()
{
for(int i = 0; i < maxn; ++i)
UF[i] = i;
}

int Kruskal()
{
int ans = 0;
init();
sort(edges, edges + m, cmp);

for(int i = 0; i < m; ++i)
{
ans = Union(edges[i].from, edges[i].to, ans, i);
}
return ans;
}
int main()
{
while(scanf("%d", &n) != EOF && n)
{
readin();
printf("%d\n", Kruskal());
}
}