B - 畅通工程再续 HDU1875

#include<iostream>
#include<algorithm>
#include<cstdio>
#include<iomanip>
#define inf 0x3f3f3f3f
const int maxn = 1e5 + 10;
using namespace std;
int father[maxn];
int find(int x) {
    return father[x] == x ? x : father[x] = find(father[x]);
}
void unite(int x, int y) {
    father[find(x)] = find(y);
}
struct rec {
    int x, y, z;
    bool friend operator<(const rec& a, const rec& b) {
        return a.z < b.z;
    }
}e[maxn];
int main()
{
    int t;
    scanf("%d", &t);
    while (t--) {
        int c;
        scanf("%d", &c);
        int x[110], y[110];
        int dis[110][110];
        for (int i = 1;i <= c;i++) {
            scanf("%d %d", &x[i], &y[i]);
        }
        int add = 1;
        for (int i = 1;i < c;i++) {
            for (int j = i + 1;j <= c;j++) {
                dis[i][j] = (x[i] - x[j]) * (x[i] - x[j]) + (y[i] - y[j]) * (y[i] - y[j]);
                if (dis[i][j] >= 100 && dis[i][j] <= 1000000) { e[++add].x = i, e[add].y = j, e[add].z = dis[i][j]; }
            }
        }
        //add--;
        for (int i = 1;i <= c;i++)father[i] = i;
        sort(e + 1, e + 1 + add);
        int cnt = 0;
        double ans = 0;
        for (int i = 1;i <= add;i++) {
            int fx = find(e[i].x), fy = find(e[i].y);
            if (fx == fy)continue;
            unite(fx, fy);
            cnt++;
            ans += sqrt(e[i].z);
        }
        ans = ans * 100;
        if (cnt == c - 1)cout << fixed << setprecision(1) << ans << endl;//printf("%.1f\n",ans);
        else puts("oh!");
    }
    return 0;
}