Language: C++

#include <iostream>
#include <algorithm>
#include <map>
#include <cmath>
#include <climits>
using namespace std;
#define ll long long int

bool bin (ll mid , vector<ll>arr , ll a  ,ll b)
{
    vector<ll>arr1(arr) ;
  for(ll i =  0 ; i < arr1.size()  ; ++i)
     {
         arr1[i] -= ((mid) * b ) ;

     }
    ll c =  0 ;
    for(ll i   = 0 ; i < arr1.size() ; ++i )
    {

        if(arr1[i] > 0)
        {
            c += ceil( (float)arr1[i] /(a-b) ) ;
          // cout<<c<<"\n" ;
        }
    }
    if( c <= mid)
        return true  ;

    return false ;
}

int main()
{
  ios::sync_with_stdio(false);cin.tie(0) ;
  ll n ; cin>>n ;
  ll a , b ;
  cin>>a>>b ;
  vector<ll>arr ;
  ll v ;
  for(ll i = 0  ; i < n ;  ++i)
    {
        cin>>v ;
        arr.push_back(v) ;
    }


   ll lo =   0 ,  hi = 10000000001 ;
    while( lo  <hi)
    {

        ll mid  = lo  + (hi  -  lo)/2  ;
        if(bin(mid , arr,a,b))
            hi = mid  ;
        else
            lo  = mid + 1  ;

    }

    cout<<lo<<"\n" ;

    return 0;
}

Compiler output:
a.cc:9:20: error: 'vector' has not been declared
    9 | bool bin (ll mid , vector<ll>arr , ll a  ,ll b)
      |                    ^~~~~~
a.cc:9:26: error: expected ',' or '...' before '<' token
    9 | bool bin (ll mid , vector<ll>arr , ll a  ,ll b)
      |                          ^
a.cc: In function 'bool bin(long long int, int)':
a.cc:11:5: error: 'vector' was not declared in this scope
   11 |     vector<ll>arr1(arr) ;
      |     ^~~~~~
a.cc:6:1: note: 'std::vector' is defined in header '<vector>'; this is probably fixable by adding '#include <vector>'
    5 | #include <climits>
  +++ |+#include <vector>
    6 | using namespace std;
a.cc:7:12: error: expected primary-expression before 'long'
    7 | #define ll long long int
      |            ^~~~
a.cc:11:12: note: in expansion of macro 'll'
   11 |     vector<ll>arr1(arr) ;
      |            ^~
a.cc:12:23: error: 'arr1' was not declared in this scope
   12 |   for(ll i =  0 ; i < arr1.size()  ; ++i)
      |                       ^~~~
a.cc:14:30: error: 'b' was not declared in this scope
   14 |          arr1[i] -= ((mid) * b ) ;
      |                              ^
a.cc:18:26: error: 'arr1' was not declared in this scope
   18 |     for(ll i   = 0 ; i < arr1.size() ; ++i )
      |                          ^~~~
a.cc:23:41: error: 'a' was not declared in this scope
   23 |             c += ceil( (float)arr1[i] /(a-b) ) ;
      |                                         ^
a.cc:23:43: error: 'b' was not declared in this scope
   23 |             c += ceil( (float)arr1[i] /(a-b) ) ;
      |                                           ^
a.cc: In function 'int main()':
a.cc:39:3: error: 'vector' was not declared in this scope
   39 |   vector<ll>arr ;
      |   ^~~~~~
a.cc:39:3: note: 'std::vector' is defined in header '<vector>'; this is probably fixable by adding '#include <vector>'
a.cc:7:12: error: expected primary-expression before 'long'
    7 | #define ll long long int
      |            ^~~~
a.cc:39:10: note: in expansion of macro 'll'
   39 |   vector<ll>arr ;
      |          ^~
a.cc:44:9: error: 'arr' was not declared in this scope
   44 |         arr.push_back(v) ;
      |         ^~~
a.cc:53:22: error: 'arr' was not declared in this scope
   53 |         if(bin(mid , arr,a,b))
      |                      ^~~