poj2728 Desert King

懒得学 Dinkelbach迭代法……二分卡过

完全图就不要用 (mathrm{O}(mlog m)) 的堆优化了……

#include <algorithm>
#include <iostream>
#include <cstring>
#include <cstdio>
#include <cmath>
using namespace std;
int n, uu[1005], vv[1005], ww[1005], din;
double a[1005][1005], dis[1005], qaq[1005][1005], pap[1005][1005];
const double eps=1e-8;
bool vis[1005];
struct Node{
	int idx;
	double val;
}nd[1100005];
double qwq(int u, int v){
	return sqrt((uu[u]-uu[v])*(uu[u]-uu[v])+(vv[u]-vv[v])*(vv[u]-vv[v]));
}
bool cmp(Node x, Node y){
	return x.val>y.val;
}
bool chk(double lim){
	for(int i=1; i<=n; i++)
		for(int j=1; j<=n; j++)
			a[i][j] = pap[i][j] - lim * qaq[i][j];
	memset(vis, 0, sizeof(vis));
	memset(dis, 127, sizeof(dis));
	dis[1] = din = 0;
	nd[++din] = (Node){1, 0.0};
	double re=0.0;/*
	while(din){
		Node x=nd[1];
		pop_heap(nd+1, nd+1+din, cmp);
		din--;
		if(vis[x.idx])	continue;
		vis[x.idx] = true;
		re += dis[x.idx];
		for(int i=1; i<=n; i++)
			if(!vis[i] && dis[i]>a[x.idx][i]){
				dis[i] = a[x.idx][i];
				nd[++din] = (Node){i, dis[i]};
				push_heap(nd+1, nd+1+din, cmp);
			}
	}*/
	for(int ii=1; ii<=n; ii++){
		int maxi=0;
		double orz=100000000.0;
		for(int i=1; i<=n; i++)
			if(!vis[i] && dis[i]<orz){
				orz = dis[i];
				maxi = i;
			}
		vis[maxi] = true;
		re += orz;
		for(int i=1; i<=n; i++){
			if(!vis[i] && dis[i]>a[maxi][i])
				dis[i] = a[maxi][i];
		}
	}
	return re<=eps;
}
int main(){
	while(scanf("%d", &n)!=EOF){
		if(!n)	break;
		for(int i=1; i<=n; i++)
			scanf("%d %d %d", &uu[i], &vv[i], &ww[i]);
		for(int i=1; i<=n; i++)
			for(int j=1; j<=n; j++){
				qaq[i][j] = qwq(i, j);
				pap[i][j] = abs(ww[i]-ww[j]);
			}
		double l=0.0, r=10000000.0, mid, re;
		while(fabs(r-l)>eps){
			mid = (l + r) / 2.0;
			if(chk(mid))	re = mid, r = mid;
			else	l = mid;
		}
		printf("%.3f
", re);
	}
	return 0;
}