$POJ$2976 $Dropping\ tests$ 01分数规划+贪心

正解:01分数规划

解题报告:

传送门!

板子题鸭,,,

显然考虑变成$a[i]-mid\cdot b[i]$,显然无脑贪心下得选出最大的$k$个然后判断是否大于0就好(,,,这么弱智真的算贪心嘛$TT$

然后就做完辣,,,

我真的$jio$得我做的题越来越水了是为什么,,,啊难过,越来越菜了可海星$TT$

#include<algorithm>
#include<iomanip>
#include<cstdio>
using namespace std;
#define il inline
#define lf double
#define gc getchar()
#define rf register lf
#define ri register int
#define rc register char
#define rb register bool
#define rp(i,x,y) for(ri i=x;i<=y;++i)

const int N=+;const lf eps=1e-;
int n,K;
bool gdgs=;
struct node{lf a,b,dat;}nod[N];

il int read()
{
    rc ch=gc;ri x=;rb y=;
    while(ch!='-' && (ch>'' || ch<''))ch=gc;
    if(ch=='-')ch=gc,y=;
    while(ch>='' && ch<='')x=(x<<)+(x<<)+(ch^''),ch=gc;
    return y?x:-x;
}
il bool cmp(node gd,node gs){return gd.dat<gs.dat;}
il bool chck(rf x)
{
    lf sum=;rp(i,,n)nod[i].dat=(lf)nod[i].a*-nod[i].b*x,sum+=nod[i].dat;sort(nod+,nod++n,cmp);
    rp(i,,K)sum-=nod[i].dat;return sum>=;
}

int main()
{
    while(gdgs)
    {
        n=read();K=read();if(!n && !K)return ;
        rp(i,,n)scanf("%lf",&nod[i].a);rp(i,,n)scanf("%lf",&nod[i].b);
        rf l=,r=;
        while(r-l>eps){rf mid=(lf)(l+r)/;if(chck(mid))l=mid;else r=mid;}
        printf("%.0f\n",l);
    }
    return ;
}

啊对了说一个这题杀我的点,,,就是$double$的输出要用$lf$,,,具体原因看评论区趴懒得贴过来了$QwQ$,,,$get$了一个新知识点呢$QwQ$