UVa 10034 - Freckles

来源：互联网发布：ib网络的网线编辑：程序博客网时间：2024/05/21 11:13

最小生成树，Kruskal算法。

代码如下：

#include <iostream>#include <algorithm>#include <cstring>#include <cstdlib>#include <cstdio>#include <cmath>using namespace std;const int MAXN = 5052;int n, p[MAXN], r[MAXN], u[MAXN], v[MAXN];double dis[MAXN], x[102], y[102], ans;int cmp(const int i, const int j){    return dis[i] < dis[j] ? 1 : 0;}int find(int i){    return p[i] == i ? i : p[i] = find(p[i]);}void Kruskal(){    ans = 0;    for(int i=0; i<n; i++)        p[i] = i;    sort(r, r+n, cmp);    for(int i=0; i<n; i++)    {        int e = r[i];        int xx = find(u[e]);        int yy = find(v[e]);        if(xx != yy)        {            ans += dis[e];            p[xx] = yy;        }    }}int main(){#ifdef test    freopen("sample.txt", "r", stdin);#endif    int t, num;    scanf("%d", &t);    while(t--)    {        n = 0;        double d1, d2;        scanf("%d", &num);        for(int i=0; i<num; i++)            scanf("%lf%lf", &x[i], &y[i]);        for(int i=0; i<num; i++)            for(int j=i+1; j<num; j++)            {                u[n] = i;                v[n] = j;                r[n] = n;                d1 = double(x[i] - x[j]);                d2 = double(y[i] - y[j]);                dis[n++] = sqrt(d1*d1+d2*d2);            }        Kruskal();        printf("%.2lf\n", ans);        if(t)            puts("");    }    return 0;}