poj-2728-Desert King-01分数规划+最小生成树

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01分数规划的题目；

由于是完全图，所以求最小生成树的时候要使用prime算法。

否则的话很容易就超时了。

#include <iostream>#include<algorithm>#include<stdio.h>#include<string.h>#include<stdlib.h>#include<queue>#include<stack>#include<math.h>using namespace std;#define maxm 1100*1100#define maxn 1100#define eps 0.000001#define zero(x) ((fabs(x)<eps?0:x))#define INF 99999999struct point{    int x;    int y;    int h;}p[maxn];double dist(int x,int y){    double xx=0;    xx=(p[x].x-p[y].x)*(p[x].x-p[y].x);    xx+=(p[x].y-p[y].y)*(p[x].y-p[y].y);    xx=xx*1.0;    return sqrt(xx);}struct list{    double h;    double l;    double s;    friend bool operator < (const list &a,const list &b)    {        return a.s<b.s;    }}maps[maxn][maxn];int m,n;double prime(double mid){    double dis[maxn];    int vis[maxn];    int i,j;    for(i=0;i<=n;i++)    {        dis[i]=INF;        vis[i]=0;    }    for(i=1;i<=n;i++)    {        for(j=1;j<=n;j++)        {            maps[i][j].s=maps[i][j].h-maps[i][j].l*mid;        }    }    dis[1]=0;    double ans;    ans=0;    while(1)    {        double minn=INF;        int ip;        for(i=1;i<=n;i++)        {            if(vis[i])continue;            if(dis[i]<minn)            {                minn=dis[i];                ip=i;            }        }        if(zero(minn-INF)==0)break;        vis[ip]=1;        ans+=minn;        for(i=1;i<=n;i++)        {            if(vis[i])continue;            dis[i]=min(dis[i],maps[ip][i].s);        }    }    return ans;}int main(){    int i,j;    while(~scanf("%d",&n)&&n)    {        m=0;        for(i=1;i<=n;i++)scanf("%d%d%d",&p[i].x,&p[i].y,&p[i].h);        for(i=1;i<=n;i++)        {            for(j=1;j<=n;j++)            {                maps[i][j].h=fabs(p[i].h-p[j].h);                maps[i][j].l=dist(i,j);            }        }        double l,r,mid;        l=0;        r=100;        mid=(l+r)/2;        while(zero(r-l)>0)        {            mid=(l+r)/2;            if(prime(mid)>0)l=mid;            else r=mid;        }        printf("%.3f\n",mid);    }    return 0;}

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