uva 10369(最小生成树)

和上一题基本一致。求解除了用了无限发射的城市最小生成树中最长的那一条边。

代码如下：

#include <iostream>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>
#define INF 0x7fffffff
#define LEN 1010
using namespace std;

typedef struct{double x, y;}POINT;
typedef struct {int a, b;double v;}ARC;

int T, n, q, top, parent[LEN];
POINT p[LEN];
ARC Arc[LEN*LEN];

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));}
bool cmp(ARC a, ARC b){return a.v<b.v;}
//UFSet
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;}

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

    scanf("%d", &T);
    while(T--){
        scanf("%d%d", &q, &n);
        for(int i=1; i<=n; i++) scanf("%lf%lf", &p[i].x, &p[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].v = dis(p[i],p[j]);top++;}
        sort(Arc, Arc+top, cmp);init();
        int cnt = 0;double ans = 0;
        for(int i=0; i<top; i++){
            if(cnt==n-q)break;
            if(Find(Arc[i].a)!=Find(Arc[i].b))
            {Union(Arc[i].a, Arc[i].b);ans= Arc[i].v;cnt++;}
        }
        printf("%.2lf
", ans);
    }
    return 0;
}