UVA 10034 - Freckles

来源：互联网发布：洗车哪个软件好编辑：程序博客网时间：2024/06/06 04:13

利用并查集求最短路，注意浮点数，再就是需要准备一下边集。

#include<stdio.h>#include<math.h>#include<stdlib.h>#define MAXN 5000 + 100#define MAXN1 100 + 10int n, m, p1, p[MAXN1],r[MAXN],u[MAXN],v[MAXN];double  w[MAXN], x[MAXN1], y[MAXN1];int cmp(const void *_p, const void *_q){    int *p = (int *)_p;    int *q = (int *)_q;    return w[*p] > w[*q] ? 1 : -1;}int find(int x) {return p[x] == x ? x : p[x] = find(p[x]);}void kruskal(){    double ans = 0;    for(int i = 0; i < m; i ++) p[i] = i;    for(int i = 0; i < p1; i ++) r[i] = i;    qsort(r, p1, sizeof(r[0]),cmp);    for(int i = 0; i < p1; i ++)    {        int e = r[i]; int s = find(u[e]); int o = find(v[e]);        if(s != o) { ans += w[e]; p[s] = o;}    }    printf("%.2lf\n",ans);}void solve(){     p1 = 0;    for(int i = 0; i < m; i ++)        for(int j = i + 1; j < m; j ++)        {            w[p1] = sqrt((x[i]-x[j])*(x[i]-x[j]) + (y[i]-y[j])*(y[i]-y[j]));            u[p1] = i;            v[p1] = j;            p1 ++;        }    kruskal();}void init(){    while(~scanf("%d",&n))        while(n --)        {            scanf("%d",&m);            for(int i = 0; i < m; i ++)                scanf("%lf%lf",&x[i],&y[i]);            solve();            if(n) puts("");        }}int main(){    init();    return  0;}

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