P1843 奶牛晒衣服

#include<iostream>
using namespace std;
long long  l,r;
long long  n,a,b;
long long  w[500001];
bool c(long long  k){
    long long  cnt=0;
    for(long long  i=1;i<=n;++i){
        long long  v=w[i]-a*k;
        if(v<0)
        v=0;
        cnt+=(v/b);
        if(v%b)
    cnt++;
    }
//    cout<<k<<endl;
    //cout<<"fddf"<<cnt<<endl;
    return cnt<=k;
}
int  main(){
    cin>>n>>a>>b;
    for(long long  i=1;i<=n;++i){
        cin>>w[i];
        r=max(r,w[i]);
    }
    while(l<=r){
        long long  mid=l+(r-l)/2;
        if(c(mid)) r=mid-1;
        else
        l=mid+1;
    }
    //cout<<l;
    cout<<l;
    return 0;
}