HDU 1875 畅通project再续 （最小生成树 水）

2
2
10 10
20 20
3
1 1
2 2
1000 1000

1414.2
oh!

总共最多有100个节点。那么边最大100*100/2，把全部 符合题意 的边都求出来，然后就是最小生成树了。

#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <math.h>
#include <stack>
#define lson o<<1, l, m
#define rson o<<1|1, m+1, r
using namespace std;
typedef long long LL;
const int maxn = 105;
const int mod = 1000000007;
int n, t, fa[105];
double q;
struct C1{
    int st, en;
    double v;
}ed[6000];
struct C2 {
    int x, y;
}in[105];
double getdis(double x1, double y1, double x2, double y2) {
    return sqrt( (x1-x2)*(x1-x2) + (y1-y2)*(y1-y2) );
}
bool cmp (C1 x, C1 y) {
    return x.v < y.v;
}
int Find (int x) {
    return x == fa[x] ? x : x = Find(fa[x]);
}
int main()
{
    scanf("%d", &t);
    while(t--) {
        int n;
        scanf("%d", &n);
        for(int i = 0; i < n; i++) scanf("%d%d", &in[i].x, &in[i].y);
        int k = 0;
        for(int i = 0; i < n-1; i++)
            for(int j = i+1; j < n; j++) {
                double tmp = getdis(in[i].x, in[i].y, in[j].x, in[j].y);
                if(tmp >= 10 && tmp <= 1000) {
                    ed[k].v = tmp*100;
                    ed[k].st = i;
                    ed[k++].en = j;
                }
            }
        sort(ed, ed+k, cmp);
        for(int i = 0; i <= 100; i++) fa[i] = i;
        double sum = 0;
        int cnt = 0;
        for(int i = 0; i <k; i++) {
            int pres = Find(ed[i].st), pree = Find(ed[i].en);
            if(pres != pree) {
                fa[pres] = pree;
                sum += ed[i].v;
                cnt++;
                if(cnt == n-1) break;
            }
        }
        if(cnt == n-1) printf("%.1lf\n", sum);
        else printf("oh!\n");
    }

    return 0;
}