Language: C++

#include<bits/stdc++.h>
using namespace std;
int main()
{
    ios_base::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);
    long long n,w;
    cin >> n >> w;
    long long weight[n];
    long long value[n];
    for(long long i = 0; i<n; i++)
    {
        cin >> weight[i] >> value[i];
    }
    map<int, map<int, int>> knap;
    for(long long i = 0; i<=n; i++)
    {
        for(long long j = 0; j<=w; j++)
        {
            if(i == 0 || j == 0)
            {
                knap[i][j] = 0;
            }
            else if(weight[i-1] <= j)
            {
                knap[i][j] = max(value[i-1]+ knap[i-1][j-weight[i-1]], knap[i-1][j]);
            }
            else
            {
                knap[i][j] = knap[i-1][j];
            }
        }
    }
    cout << knap[n][w];
}


Compiler output:
a.cc: In function 'int main()':
a.cc:27:33: error: no matching function for call to 'max(long long int, std::map<int, int>::mapped_type&)'
   27 |                 knap[i][j] = max(value[i-1]+ knap[i-1][j-weight[i-1]], knap[i-1][j]);
      |                              ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In file included 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_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:27:33: note:   deduced conflicting types for parameter 'const _Tp' ('long long int' and 'std::map<int, int>::mapped_type' {aka 'int'})
   27 |                 knap[i][j] = max(value[i-1]+ knap[i-1][j-weight[i-1]], knap[i-1][j]);
      |                              ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
/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:
/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:27:33: note:   mismatched types 'std::initializer_list<_Tp>' and 'long long int'
   27 |                 knap[i][j] = max(value[i-1]+ knap[i-1][j-weight[i-1]], knap[i-1][j]);
      |                              ~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~