[luogu1843] 奶牛晒衣服

题目链接

题解：二分后变为可行性问题

#include <iostream>#include <cstdio>#include <algorithm>#include <cmath>using namespace std;int n,P,Q,l,r,mid,ans;int w[500005];bool ok(int x){    int t=0;    for(int i=1;i<=n;i++)    {        if(x*P>=w[i]) continue;        else {            t+=(w[i]-x*P)/Q;            if((w[i]-x*P)%Q) t++;        }    }    return t<=x;}int main(){    cin>>n>>P>>Q;    for(int i=1;i<=n;i++)    scanf("%d",&w[i]);    l=1,r=1000000;    while(l<=r){        mid=(l+r)>>1;        if(ok(mid))        r=mid-1,ans=mid;        else         l=mid+1;    }    cout<<ans<<endl;}