uva 10034（最小生成树）

记得在哪里做过一遍，最简单的最小生成树，直接用kruskal秒掉了。

代码如下：

#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstring>
#include <cstdlib>
#include <algorithm>
#define LEN 110
using namespace std;

typedef struct {
    double x, y;
}POINT;

POINT Point[LEN];

typedef struct {
    int a, b;
    double w;
}ARC;

ARC Arc[LEN*LEN];
int top, n;

inline double dis(POINT a, POINT b){
    return sqrt((a.x-b.x)*(a.x-b.x)+(a.y-b.y)*(a.y-b.y));
}

//UFSet
int parent[LEN];

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

int Find(int x){
    return parent[x]==x?x:parent[x]=Find(parent[x]);
}

void Union(int a, int b){
    int pa = Find(a), pb = Find(b);
    if(pa!=pb) parent[pa] = pb;
}

//kurskal
bool cmp(ARC a, ARC b){
    return a.w<b.w;
}

double kurskal()
{
    sort(Arc, Arc+top, cmp);
    init();
    double ret = 0;
    int cnt = 0;
    for(int i=0; i<top; i++){
        if(cnt == n-1) break;
        if(Find(Arc[i].a)!=Find(Arc[i].b)){
            cnt++;
            Union(Arc[i].a, Arc[i].b);
            ret+=Arc[i].w;
        }
    }
    return ret;
}

int main()
{
//    freopen("in.txt", "r", stdin);

    int T;
    scanf("%d", &T);
    while(T--){
        scanf("%d", &n);
        for(int i=1; i<=n; i++){
            scanf("%lf%lf", &Point[i].x, &Point[i].y);
        }
        top = 0;
        for(int i=1; i<=n; i++){
            for(int j=i+1; j<=n; j++){
                Arc[top].a = i;
                Arc[top].b = j;
                Arc[top].w = dis(Point[i],Point[j]);
                top ++;
            }
        }
        double ans = kurskal();
        printf("%.2lf
", ans);
        if(T) printf("
");
    }
    return 0;
}