UVA 10034 - Freckles

#include<stdio.h>
#include<math.h>
#include<stdlib.h>
#define MAXN 5000 + 100
#define MAXN1 100 + 10
int n, m, p1, p[MAXN1],r[MAXN],u[MAXN],v[MAXN];
double  w[MAXN], x[MAXN1], y[MAXN1];

int cmp(const void *_p, const void *_q)
{
int *p = (int *)_p;
int *q = (int *)_q;
return w[*p] > w[*q] ? 1 : -1;
}

int find(int x) {return p[x] == x ? x : p[x] = find(p[x]);}

void kruskal()
{
double ans = 0;
for(int i = 0; i < m; i ++) p[i] = i;
for(int i = 0; i < p1; i ++) r[i] = i;
qsort(r, p1, sizeof(r[0]),cmp);
for(int i = 0; i < p1; i ++)
{
int e = r[i]; int s = find(u[e]); int o = find(v[e]);
if(s != o) { ans += w[e]; p[s] = o;}
}
printf("%.2lf\n",ans);
}

void solve()
{
p1 = 0;
for(int i = 0; i < m; i ++)
for(int j = i + 1; j < m; j ++)
{
w[p1] = sqrt((x[i]-x[j])*(x[i]-x[j]) + (y[i]-y[j])*(y[i]-y[j]));
u[p1] = i;
v[p1] = j;
p1 ++;
}
kruskal();
}

void init()
{
while(~scanf("%d",&n))
while(n --)
{
scanf("%d",&m);
for(int i = 0; i < m; i ++)
scanf("%lf%lf",&x[i],&y[i]);
solve();
if(n) puts("");
}
}

int main()
{
init();
return  0;
}