Language: C++

#define _USE_MATH_DEFINES
#include <algorithm>
#include <array>
#include <bitset>
#include <cassert>
#include <cctype>
#include <climits>
#include <clocale>
#include <cmath>
#include <complex>
#include <cstdio>
#include <cstdlib>
#include <ctime>
#include <deque>
#include <fstream>
#include <functional>
#include <iomanip>
#include <iostream>
#include <iterator>
#include <list>
#include <map>
#include <numeric>
#include <queue>
#include <regex>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <tuple>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

const int MOD = 1000000007; 
const int INF = 1000000000; //1e9
const int NIL = -1;
const long long LINF = 1000000000000000000; // 1e18
const long double EPS = 1E-10;

template<class T, class S> inline bool chmax(T &a, const S &b){
    if(a < b){
        a = b; return true;
    }
    return false;
}
template<class T, class S> inline bool chmin(T &a, const S &b){
    if(b < a){
        a = b; return true;
    }
    return false;
}






int main(){
    int N, A, mx; std::cin >> N >> A;
    mx = A;
    std::vector<int> x(N);
    for(int i(0); i < N; ++i){
        std::cin >> x[i];
        chmax(mx, x);
    }
    //dp[i][j][k]: x[0],..,x[i-1]からj枚で和がk
    std::vector<std::vector<std::vector<long long>>> dp(N+1, 
     std::vector<std::vector<long long>>(N+1, 
     std::vector<long long>(N*mx + 1, 0)));
    dp[0][0][0] = 1;
    for(int i(1); i <= N; ++i){
        for(int j(0); j <= N; ++j){
            for(int k(0), k_len(N*mx); k <= k_len; ++k){
                dp[i][j][k] = dp[i-1][j][k];
                if(j && k >= x[i-1])
                    dp[i][j][k] += dp[i-1][j-1][k - x[i-1]];
            }
        }
    }
    long long ans(0);
    for(int i(1); i <= N; ++i){
        ans += dp[N][i][A*i];
    }
    std::cout << ans << std::endl;
    return 0;
}


Compiler output:
a.cc: In instantiation of 'bool chmax(T&, const S&) [with T = int; S = std::vector<int>]':
a.cc:65:14:   required from here
   65 |         chmax(mx, x);
      |         ~~~~~^~~~~~~
a.cc:42:10: error: no match for 'operator<' (operand types are 'int' and 'const std::vector<int>')
   42 |     if(a < b){
      |        ~~^~~
In file included from /usr/include/c++/14/regex:68,
                 from a.cc:24:
/usr/include/c++/14/bits/regex.h:1143:5: note: candidate: 'template<class _BiIter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const sub_match<_BiIter>&)'
 1143 |     operator<(const sub_match<_BiIter>& __lhs, const sub_match<_BiIter>& __rhs)
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1143:5: note:   template argument deduction/substitution failed:
a.cc:42:10: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
   42 |     if(a < b){
      |        ~~^~~
/usr/include/c++/14/bits/regex.h:1224:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator<(__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&, const sub_match<_BiIter>&)'
 1224 |     operator<(const __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1224:5: note:   template argument deduction/substitution failed:
a.cc:42:10: note:   mismatched types 'std::__cxx11::__sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>' and 'int'
   42 |     if(a < b){
      |        ~~^~~
/usr/include/c++/14/bits/regex.h:1317:5: note: candidate: 'template<class _Bi_iter, class _Ch_traits, class _Ch_alloc> bool std::__cxx11::operator<(const sub_match<_BiIter>&, __sub_match_string<_Bi_iter, _Ch_traits, _Ch_alloc>&)'
 1317 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1317:5: note:   template argument deduction/substitution failed:
a.cc:42:10: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
   42 |     if(a < b){
      |        ~~^~~
/usr/include/c++/14/bits/regex.h:1391:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const typename std::iterator_traits<_Iter>::value_type*, const sub_match<_BiIter>&)'
 1391 |     operator<(typename iterator_traits<_Bi_iter>::value_type const* __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1391:5: note:   template argument deduction/substitution failed:
a.cc:42:10: note:   'const std::vector<int>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   42 |     if(a < b){
      |        ~~^~~
/usr/include/c++/14/bits/regex.h:1485:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type*)'
 1485 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1485:5: note:   template argument deduction/substitution failed:
a.cc:42:10: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
   42 |     if(a < b){
      |        ~~^~~
/usr/include/c++/14/bits/regex.h:1560:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const typename std::iterator_traits<_Iter>::value_type&, const sub_match<_BiIter>&)'
 1560 |     operator<(typename iterator_traits<_Bi_iter>::value_type const& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1560:5: note:   template argument deduction/substitution failed:
a.cc:42:10: note:   'const std::vector<int>' is not derived from 'const std::__cxx11::sub_match<_BiIter>'
   42 |     if(a < b){
      |        ~~^~~
/usr/include/c++/14/bits/regex.h:1660:5: note: candidate: 'template<class _Bi_iter> bool std::__cxx11::operator<(const sub_match<_BiIter>&, const typename std::iterator_traits<_Iter>::value_type&)'
 1660 |     operator<(const sub_match<_Bi_iter>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/regex.h:1660:5: note:   template argument deduction/substitution failed:
a.cc:42:10: note:   mismatched types 'const std::__cxx11::sub_match<_BiIter>' and 'int'
   42 |     if(a < b){
      |        ~~^~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/algorithm:60,
                 from a.cc:2:
/usr/include/c++/14/bits/stl_pair.h:1045:5: note: candidate: 'template<class _T1, class _T2> constexpr bool std::operator<(const pair<_T1, _T2>&, const pair<_T1, _T2>&)'
 1045 |     operator<(const pair<_T1, _T2>& __x, const pair<_T1, _T2>& __y)
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_pair.h:1045:5: note:   template argument deduction/substitution failed:
a.cc:42:10: note:   mismatched types 'const std::pair<_T1, _T2>' and 'int'
   42 |     if(a < b){
      |        ~~^~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:67:
/usr/include/c++/14/bits/stl_iterator.h:448:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_Iterator>&)'
  448 |     operator<(const reverse_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:448:5: note:   template argument deduction/substitution failed:
a.cc:42:10: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'int'
   42 |     if(a < b){
      |        ~~^~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const reverse_iterator<_Iterator>&, const reverse_iterator<_IteratorR>&)'
  493 |     operator<(const reverse_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:493:5: note:   template argument deduction/substitution failed:
a.cc:42:10: note:   mismatched types 'const std::reverse_iterator<_Iterator>' and 'int'
   42 |     if(a < b){
      |        ~~^~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note: candidate: 'template<class _IteratorL, class _IteratorR> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorR>&)'
 1694 |     operator<(const move_iterator<_IteratorL>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1694:5: note:   template argument deduction/substitution failed:
a.cc:42:10: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'int'
   42 |     if(a < b){
      |        ~~^~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note: candidate: 'template<class _Iterator> constexpr bool std::operator<(const move_iterator<_IteratorL>&, const move_iterator<_IteratorL>&)'
 1760 |     operator<(const move_iterator<_Iterator>& __x,
      |     ^~~~~~~~
/usr/include/c++/14/bits/stl_iterator.h:1760:5: note:   template argument deduction/substitution failed:
a.cc:42:10: note:   mismatched types 'const std::move_iterator<_IteratorL>' and 'int'
   42 |     if(a < b){
      |        ~~^~~
In file included from a.cc:3:
/usr/include/c++/14/array:339:5: note: candidate: 'template<class _Tp, long unsigned int _Nm> bool std::operator<(const array<_Tp, _Nm>&, const array<_Tp, _Nm>&)'
  339 |     operator<(const array<_Tp, _Nm>& __a, const array<_Tp, _Nm>& __b)
      |     ^~~~~~~~
/usr/include/c++/14/array:339:5: note:   template argument deduction/substitution failed:
a.cc:42:10: note:   mismatched types 'const std::array<_Tp, _Nm>' and 'int'
   42 |     if(a < b){
      |        ~~^~~
In file included from /usr/include/c++/14/bits/basic_string.h:47,
                 from /usr/include/c++/14/string:54,
                 from /usr/include/c++/14/bitset:52,
                 from a.cc:4:
/usr/include/c++/14/string_view:673:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(basic_string_view<_CharT, _Traits>, basic_string_view<_CharT, _Traits>)'
  673 |     operator< (basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:673:5: note:   template argument deduction/substitution failed:
a.cc:42:10: note:   mismatched types 'std::basic_string_view<_CharT, _Traits>' and 'int'
   42 |     if(a < b){
      |        ~~^~~
/usr/include/c++/14/string_view:680:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(basic_string_view<_CharT, _Traits>, __type_identity_t<basic_string_view<_CharT, _Traits> >)'
  680 |     operator< (basic_string_view<_CharT, _Traits> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:680:5: note:   template argument deduction/substitution failed:
a.cc:42:10: note:   mismatched types 'std::basic_string_view<_CharT, _Traits>' and 'int'
   42 |     if(a < b){
      |        ~~^~~
/usr/include/c++/14/string_view:688:5: note: candidate: 'template<class _CharT, class _Traits> constexpr bool std::operator<(__type_identity_t<basic_string_view<_CharT, _Traits> >, basic_string_view<_CharT, _Traits>)'
  688 |     operator< (__type_identity_t<basic_string_view<_CharT, _Traits>> __x,
      |     ^~~~~~~~
/usr/include/c++/14/string_view:688:5: note:   template argument deduction/substitution failed:
a.cc:42:10: note:   'std::vector<int>' is not derived from 'std::basic_string_view<_CharT, _Traits>'
   42 |     if(a < b){
      |        ~~^~~
/usr/include/c++/14/bits/basic_string.h:3874:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const __cxx11::basic_string<_CharT, _Traits, _Allocator>&)'
 3874 |     operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3874:5: note:   template argument deduction/substitution failed:
a.cc:42:10: note:   mismatched types 'const std::__cxx11::basic_string<_CharT, _Traits, _Allocator>' and 'int'
   42 |     if(a < b){
      |        ~~^~~
/usr/include/c++/14/bits/basic_string.h:3888:5: note: candidate: 'template<class _CharT, class _Traits, class _Alloc> bool std::operator<(const __cxx11::basic_string<_CharT, _Traits, _Allocator>&, const _CharT*)'
 3888 |     operator<(const basic_string<_CharT, _Traits, _Alloc>& __lhs,
      |     ^~~~~~~~
/usr/include/c++/14/bits/basic_string.h:3888:5: note:   template argume