Language: C++

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N = 2e5 + 10;
ll n, a[N], pre[N];
ll m, sum[N], ans;
ll check(int x) {
    ll cnt = 0;
    ans = 0;
    for(int i = 0; i < n; i++) {
        cnt += pre[max(0, x-a[i])];
        ans += sum[max(0, x-a[i])] + (ll)a[i]*pre[max(0, x-a[i])];
    }
    return cnt;
}
int main() {
    cin >> n >> m;
    for(int i = 0; i < n; i++) {
        cin >> a[i];
        pre[a[i]]++;
    }
    for(int i = N-2; i >= 0; i--) {
        sum[i] = sum[i+1] + (ll)i*pre[i];
        pre[i] += pre[i+1];
    }
    int l = 1, r = 200000, res = 0;
    while(l <= r) {
        int mid = (l+r)/2;
        if(check(mid) >= m) {
            res = mid;
            l = mid+1;
        } else {
            r = mid-1;
        }
    }
    ll cnt = check(res);
    cout << ans-(cnt-m)*res << '\n';
    return 0;
}

Compiler output:
a.cc: In function 'll check(int)':
a.cc:11:23: error: no matching function for call to 'max(int, ll)'
   11 |         cnt += pre[max(0, x-a[i])];
      |                    ~~~^~~~~~~~~~~
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:11:23: note:   deduced conflicting types for parameter 'const _Tp' ('int' and 'll' {aka 'long long int'})
   11 |         cnt += pre[max(0, x-a[i])];
      |                    ~~~^~~~~~~~~~~
/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:11:23: note:   mismatched types 'std::initializer_list<_Tp>' and 'int'
   11 |         cnt += pre[max(0, x-a[i])];
      |                    ~~~^~~~~~~~~~~
a.cc:12:23: error: no matching function for call to 'max(int, ll)'
   12 |         ans += sum[max(0, x-a[i])] + (ll)a[i]*pre[max(0, x-a[i])];
      |                    ~~~^~~~~~~~~~~
/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:12:23: note:   deduced conflicting types for parameter 'const _Tp' ('int' and 'll' {aka 'long long int'})
   12 |         ans += sum[max(0, x-a[i])] + (ll)a[i]*pre[max(0, x-a[i])];
      |                    ~~~^~~~~~~~~~~
/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:12:23: note:   mismatched types 'std::initializer_list<_Tp>' and 'int'
   12 |         ans += sum[max(0, x-a[i])] + (ll)a[i]*pre[max(0, x-a[i])];
      |                    ~~~^~~~~~~~~~~
a.cc:12:54: error: no matching function for call to 'max(int, ll)'
   12 |         ans += sum[max(0, x-a[i])] + (ll)a[i]*pre[max(0, x-a[i])];
      |                                                   ~~~^~~~~~~~~~~
/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:12:54: note:   deduced conflicting types for parameter 'const _Tp' ('int' and 'll' {aka 'long long int'})
   12 |         ans += sum[max(0, x-a[i])] + (ll)a[i]*pre[max(0, x-a[i])];
      |                                                   ~~~^~~~~~~~~~~
/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:12:54: note:   mismatched types 'std::initializer_list<_Tp>' and 'int'
   12 |         ans += sum[max(0, x-a[i])] + (ll)a[i]*pre[max(0, x-a[i])];
      |                                                   ~~~^~~~~~~~~~~