hdu1875 畅通工程再续 暴力+基础最小生成树

#include<cstdio>
#include<cmath>
#include<algorithm>
using namespace std;

const int maxn = 100005;
const int L = 100;
const int R = 100000;
int t, n, m, ans;
double total;
struct node
{
    int x, y;
    int cost;
}pot[maxn];
int fa[maxn];
int px[maxn], py[maxn];

int cal()
{
    int i, j, tx, ty, len, pos;
    pos = 0;
    for (i = 0; i<n; i++)
    {
        for (j = i + 1; j<n; j++)
        {
            tx = px[i] - px[j];
            ty = py[i] - py[j];
            len = tx*tx + ty*ty;
            if (len >= L&&len <= R)
            {
                pot[pos].x = i;
                pot[pos].y = j;
                pot[pos].cost = len;
                pos++;
            }
        }
    }
    return pos;
}

void init()
{
    total = 0.0;
    ans = n - 1;
    for (int i = 0; i <= n; i++)
    {
        fa[i] = i;
    }
}

bool cmp(node a, node b)
{
    return a.cost<b.cost;
}

int find(int x)
{
    if (x != fa[x])
        return fa[x] = find(fa[x]);
    return fa[x];
}

int join(int x, int y)
{
    int flag = 0;
    if (x != y)
    {
        ans--;
        fa[x] = y;
        flag = 1;
    }
    return flag;
}

int main()
{
    scanf("%d", &t);
    while (t--)
    {
        scanf("%d", &n);
        init();
        for (int i = 0; i<n; i++)
        {
            scanf("%d %d", &px[i], &py[i]);
        }
        int len = cal();
        if (len<n - 1)
        {
            printf("oh!
");
            continue;
        }
        sort(pot, pot + len, cmp);
        for (int i = 0; i<len; i++)
        {
            int fx, fy;
            fx = find(pot[i].x);
            fy = find(pot[i].y);
            if (join(fx, fy) == 1)
            {
                total += sqrt(pot[i].cost*1.0);
            }
        }
        if (ans != 0)
        {
            printf("oh!
");
            continue;
        }
        printf("%.1lf
", total * 100);
    }
    return 0;
}