#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
using namespace std;
struct _Node{
double x, y, z, r;
_Node(){}
_Node(double _x, double _y, double _z, double _r): x(_x), y(_y), z(_z), r(_r){};
};
struct _Edge{
int from, to;
double dist;
_Edge(){};
_Edge(int _from, int _to, double _dist): from(_from), to(_to), dist(_dist){};
};
const int MAXN = 105;
const int MAXM = 105*104;
int f[MAXN];
_Edge edge[MAXM];
_Node node[MAXN];
int find(int x){
return f[x] == -1 ? x : f[x] = find(f[x]);
}
bool cmp(_Edge e1, _Edge e2){
return e1.dist < e2.dist;
}
double Kruskal(int cnt, int n){
memset(f, -1, sizeof(f));
sort(edge, edge + cnt, cmp);
double res = 0;
int t = 0;
for(int i = 0; i < cnt; ++i){
int a = find(edge[i].from);
int b = find(edge[i].to);
if(a != b){
f[a] = b;
res += edge[i].dist;
t++;
}
if(t == n - 1) break;
}
if(t < n - 1) return -1;
else return res;
}
double getDist(int i, int j){
double dx = node[i].x - node[j].x;
double dy = node[i].y - node[j].y;
double dz = node[i].z - node[j].z;
double dist = sqrt(dx*dx + dy*dy + dz*dz);
double t = dist - node[i].r - node[j].r;
if(t <= 0) return 0;
else return t;
}
int main(){
int n;
while(cin >> n && n){
for(int i = 0; i < n; ++i) cin >> node[i].x >> node[i].y >> node[i].z >> node[i].r;
int cnt = 0;
for(int i = 0; i < n; ++i)
for(int j = 0; j < n; ++j) {
if(i != j){
edge[cnt].from = i;
edge[cnt].to = j;
edge[cnt++].dist = getDist(i, j);
}
}
printf("%.3f\n", Kruskal(cnt, n));
}
return 0;
}
POJ-2031(Building a Space Station) Kruskal
最新推荐文章于 2020-06-02 10:49:09 发布