Language: C++

#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pb push_back
#define all(x) (x).begin(), (x).end()
#define db(x) cerr << #x << "=" << x << "\n"
#define db2(x, y) cerr << #x << "=" << x << " , " << #y << "=" << y << "\n"
#define db3(a,b,c) cerr<<#a<<"="<<a<<","<<#b<<"="<<b<<","<<#c<<"="<<c<<"\n"
#define dbv(v) cerr << #v << ":"; for (auto ite : v) cerr << ite << ' '; cerr <<"\n"
#define dbvp(v) cerr << #v << ":"; for (auto ite : v) cerr << "{"  << ite.f << ',' << ite.s << "} "; cerr << "\n"
#define dba(a,ss,ee) cerr << #a << ":"; FOR(ite,ss,ee) cerr << a[ite] << ' '; cerr << "\n"
int n, ans;
vector <int> l;
int32_t main() {
    ios_base::sync_with_stdio(0); cin.tie(0);
    ans = 0;
    cin >> n;
    for(int i = 0; i < n; ++i) {
        int x; cin >> x;
        l.pb(x);
    }
    sort(all(l));

    for(int i = n-1; i >= 2; --i) {
        for(int j = i-1; j >= 1; --j) {
			cerr << i << ' ' << j << endl;
            auto a = lower_bound(all(l), l[i]-l[j]);
            auto b = l.begin() + j - 1;
            db2(a-l.begin(),b-l.begin());
            //cerr << *a << ' ' << *b << endl;
			ans +=max(b-a,0);
        }
    }
    cout << ans;
}


Compiler output:
a.cc: In function 'int32_t main()':
a.cc:31:34: error: no matching function for call to 'max(__gnu_cxx::__normal_iterator<long long int*, std::vector<long long int> >::difference_type, int)'
   31 |                         ans +=max(b-a,0);
      |                               ~~~^~~~~~~
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:31:34: note:   deduced conflicting types for parameter 'const _Tp' ('long int' and 'int')
   31 |                         ans +=max(b-a,0);
      |                               ~~~^~~~~~~
/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:31:34: note:   mismatched types 'std::initializer_list<_Tp>' and 'long int'
   31 |                         ans +=max(b-a,0);
      |                               ~~~^~~~~~~