poj 3111 K Best

本来是条很简单的题，可是细节好多，不会处理，神烦。（最大化平均值）

1.精度问题，需要设置到1e-6内

2.储存问题，把a外置就不行了，，，why??

#include <cstdio>#include <iostream>#include <algorithm>#include <cmath>using namespace std;const int maxn=1000000+10;const int INF=1e7+1;struct node{int t;double sum;}s[maxn];int a[maxn],v[maxn],w[maxn],n,k;int cmp(node l1,node l2){return l1.sum>l2.sum;}bool C(double d){    for(int i=1;i<=n;i++)    {    s[i].t=i;    s[i].sum=v[i]-d*w[i];}sort(s+1,s+n+1,cmp);double res=0;for(int i=1;i<=k;i++)  //不能把a[i]和res分开写，细节好多，好烦 {res+=s[i].sum;a[i]=s[i].t; } return res>=0;} void solve(){double lb=0,ub=INF;while(ub-lb>1e-6)  //精度要求好高 {double mid=(lb+ub)/2;if(C(mid)) lb=mid;else ub=mid;}for(int i=1;i<=k;i++)cout<<a[i]<<" ";cout<<endl;}int main(){    while(~scanf("%d%d",&n,&k)){    for(int i=1;i<=n;i++)    scanf("%d%d",&v[i],&w[i]);     solve();}   }