Language: C++

#include<iostream>
#include<utility>
#include<algorithm>
#include<cstdio>
using namespace std;

int main()
{
  int n,m,k;
  pair<int,int> p[20];
  int a,b,c;
  int i,j,l;

  cin>>n>>m>>k;

  for(i=0;i<n;i++)
    cin>>p[i].first;
  for(i=0;i<n;i++)
    cin>>p[i].second;

  sort(p,p+n);

  if(k==1){
    a=min(m,p[n-1].second);
    cout<<p[n-1].first*a+m-a<<endl;;

  }else if(k==2){ 

    long long dp[20][20]={};
    int ans=0;
    for(i=0;i<n-1;i++)
      for(j=i+1;j<n;j++){
	a=min(p[j].second,m);
	b=min(p[i].second,m-a);
	dp[i][j]=p[j].first*a+p[i].first*b;
	ans=max(ans,dp[i][j]+m-a-b);
      }
    cout<<ans<<endl;


  }else if(k==3){

    long long dp[20][20][20]={};
    int ans=0;

    for(i=0;i<n-2;i++)
      for(j=i+1;j<n-1;j++)
	for(l=j+1;l<n;l++){
	  a=min(p[l].second,m);
	  b=min(p[j].second,m-a);
	  c=min(p[i].second,m-a-b);
	  dp[i][j][l]=p[l].first*a+p[j].first*b+p[i].first*c;
	  ans=max(ans,dp[i][j][l]+m-a-b-c);

	}

    cout<<ans<<endl;
  }

}

Compiler output:
a.cc: In function 'int main()':
a.cc:36:16: error: no matching function for call to 'max(int&, long long int)'
   36 |         ans=max(ans,dp[i][j]+m-a-b);
      |             ~~~^~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/c++/14/string:51,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/bits/stl_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:36:16: note:   deduced conflicting types for parameter 'const _Tp' ('int' and 'long long int')
   36 |         ans=max(ans,dp[i][j]+m-a-b);
      |             ~~~^~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
In file included from /usr/include/c++/14/algorithm:61,
                 from a.cc:3:
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:36:16: note:   mismatched types 'std::initializer_list<_Tp>' and 'int'
   36 |         ans=max(ans,dp[i][j]+m-a-b);
      |             ~~~^~~~~~~~~~~~~~~~~~~~
a.cc:53:18: error: no matching function for call to 'max(int&, long long int)'
   53 |           ans=max(ans,dp[i][j][l]+m-a-b-c);
      |               ~~~^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note: candidate: 'template<class _Tp> constexpr const _Tp& std::max(const _Tp&, const _Tp&)'
  257 |     max(const _Tp& __a, const _Tp& __b)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:257:5: note:   template argument deduction/substitution failed:
a.cc:53:18: note:   deduced conflicting types for parameter 'const _Tp' ('int' and 'long long int')
   53 |           ans=max(ans,dp[i][j][l]+m-a-b-c);
      |               ~~~^~~~~~~~~~~~~~~~~~~~~~~~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note: candidate: 'template<class _Tp, class _Compare> constexpr const _Tp& std::max(const _Tp&, const _Tp&, _Compare)'
  303 |     max(const _Tp& __a, const _Tp& __b, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algobase.h:303:5: note:   candidate expects 3 arguments, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5706:5: note: candidate: 'template<class _Tp> constexpr _Tp std::max(initializer_list<_Tp>)'
 5706 |     max(initializer_list<_Tp> __l)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5706:5: note:   candidate expects 1 argument, 2 provided
/usr/include/c++/14/bits/stl_algo.h:5716:5: note: candidate: 'template<class _Tp, class _Compare> constexpr _Tp std::max(initializer_list<_Tp>, _Compare)'
 5716 |     max(initializer_list<_Tp> __l, _Compare __comp)
      |     ^~~
/usr/include/c++/14/bits/stl_algo.h:5716:5: note:   template argument deduction/substitution failed:
a.cc:53:18: note:   mismatched types 'std::initializer_list<_Tp>' and 'int'
   53 |           ans=max(ans,dp[i][j][l]+m-a-b-c);
      |               ~~~^~~~~~~~~~~~~~~~~~~~~~~~~