Language: C++

#include <bits/stdc++.h>
using namespace std;
#define fastt ios_base::sync_with_stdio(false);cin.tie(NULL);
#define enl "\n"
#define ll long long
#define pb push_back
#define fi first
#define se second
#define vvl vector<vector<ll>> 
#define vl vector<ll> 
#define vpll vector<pair<ll,ll>>
#define all(x) x.begin(),x.end()
#define ffor(i,n) for(ll i = 0; i < n; ++i)
#define PI 3.14159265 
ll mod=1e9+7;

 int main(){
     fastt;
     ll i,j,k;
   ll n,W;
   cin>>n>>w;
   vector<ll> v(n),w(n);
   for(i=0;i<n;i++){
     cin>>w[i]>>v[i];
   }
   vector<pair<double,int>> vp(n);
   for(i=0;i<n;i++){
   		vp[i]={v[i]*1.0/w[i],i};
   }
   sort(all(vp));j=0;k=0;
   for(i=n-1;i>=0;i--){
   		j+=w[vp[i].se];
     if(j<=W){
     	k+=v[vp[i].se];
     }
   }
   cout<<k<<enl;
 }


Compiler output:
a.cc: In function 'int main()':
a.cc:21:12: error: 'w' was not declared in this scope
   21 |    cin>>n>>w;
      |            ^
a.cc:28:39: error: no match for 'operator=' (operand types are '__gnu_cxx::__alloc_traits<std::allocator<std::pair<double, int> >, std::pair<double, int> >::value_type' {aka 'std::pair<double, int>'} and '<brace-enclosed initializer list>')
   28 |                 vp[i]={v[i]*1.0/w[i],i};
      |                                       ^
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/algorithm:60,
                 from /usr/include/x86_64-linux-gnu/c++/14/bits/stdc++.h:51,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_pair.h:946:9: note: candidate: 'template<class _U1, class _U2> typename std::enable_if<std::__and_<std::is_assignable<_T1&, const _U1&>, std::is_assignable<_T2&, const _U2&> >::value, std::pair<_T1, _T2>&>::type std::pair<_T1, _T2>::operator=(const std::pair<_U1, _U2>&) [with _U2 = _U1; _T1 = double; _T2 = int]'
  946 |         operator=(const pair<_U1, _U2>& __p)
      |         ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:946:9: note:   template argument deduction/substitution failed:
a.cc:28:39: note:   couldn't deduce template parameter '_U1'
   28 |                 vp[i]={v[i]*1.0/w[i],i};
      |                                       ^
/usr/include/c++/14/bits/stl_pair.h:957:9: note: candidate: 'template<class _U1, class _U2> typename std::enable_if<std::__and_<std::is_assignable<_T1&, _U1&&>, std::is_assignable<_T2&, _U2&&> >::value, std::pair<_T1, _T2>&>::type std::pair<_T1, _T2>::operator=(std::pair<_U1, _U2>&&) [with _U2 = _U1; _T1 = double; _T2 = int]'
  957 |         operator=(pair<_U1, _U2>&& __p)
      |         ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:957:9: note:   template argument deduction/substitution failed:
a.cc:28:39: note:   couldn't deduce template parameter '_U1'
   28 |                 vp[i]={v[i]*1.0/w[i],i};
      |                                       ^
/usr/include/c++/14/bits/stl_pair.h:921:7: note: candidate: 'std::pair<_T1, _T2>& std::pair<_T1, _T2>::operator=(std::__conditional_t<((bool)std::__and_<std::is_copy_assignable<_T1>, std::is_copy_assignable<_T2> >::value), const std::pair<_T1, _T2>&, const std::__nonesuch&>) [with _T1 = double; _T2 = int; std::__conditional_t<((bool)std::__and_<std::is_copy_assignable<_T1>, std::is_copy_assignable<_T2> >::value), const std::pair<_T1, _T2>&, const std::__nonesuch&> = const std::pair<double, int>&]'
  921 |       operator=(__conditional_t<__and_<is_copy_assignable<_T1>,
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:923:65: note:   no known conversion for argument 1 from '<brace-enclosed initializer list>' to 'std::__conditional_t<true, const std::pair<double, int>&, const std::__nonesuch&>' {aka 'const std::pair<double, int>&'}
  921 |       operator=(__conditional_t<__and_<is_copy_assignable<_T1>,
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~  
  922 |                                        is_copy_assignable<_T2>>::value,
      |                                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  923 |                                 const pair&, const __nonesuch&> __p)
      |                                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^~~
/usr/include/c++/14/bits/stl_pair.h:931:7: note: candidate: 'std::pair<_T1, _T2>& std::pair<_T1, _T2>::operator=(std::__conditional_t<((bool)std::__and_<std::is_move_assignable<_Tp>, std::is_move_assignable<_T2> >::value), std::pair<_T1, _T2>&&, std::__nonesuch&&>) [with _T1 = double; _T2 = int; std::__conditional_t<((bool)std::__and_<std::is_move_assignable<_Tp>, std::is_move_assignable<_T2> >::value), std::pair<_T1, _T2>&&, std::__nonesuch&&> = std::pair<double, int>&&]'
  931 |       operator=(__conditional_t<__and_<is_move_assignable<_T1>,
      |       ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:933:55: note:   no known conversion for argument 1 from '<brace-enclosed initializer list>' to 'std::__conditional_t<true, std::pair<double, int>&&, std::__nonesuch&&>' {aka 'std::pair<double, int>&&'}
  931 |       operator=(__conditional_t<__and_<is_move_assignable<_T1>,
      |                 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  932 |                                        is_move_assignable<_T2>>::value,
      |                                        ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  933 |                                 pair&&, __nonesuch&&> __p)
      |                                 ~~~~~~~~~~~~~~~~~~~~~~^~~