Submission #3607123

---

Source Code Expand

#include <iostream>
#include <vector>
#include <algorithm>

#define MOD 1000000007

using namespace std;

int main() {
    ll n, ans = 1;
    cin >> n;
    vector<ll> a(n);
    for (ll i = 0; i < n; ++i) cin >> a.at(i);
    sort(a.begin(), a.end());
    for (ll i = n - 1; i >= 0; --i) {
        if (a.at(i) != (i + n % 2) / 2 * 2 + (n - 1) % 2) {
            cout << 0 << endl;
            return 0;
        }
    }
    for (ll i = 0; i < n / 2; ++i) ans = ans * 2 % MOD;
    cout << ans << endl;
    return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:10:5: error: ‘ll’ was not declared in this scope
     ll n, ans = 1;
     ^
./Main.cpp:11:12: error: ‘n’ was not declared in this scope
     cin >> n;
            ^
./Main.cpp:12:12: error: the value of ‘ll’ is not usable in a constant expression
     vector<ll> a(n);
            ^
./Main.cpp:10:5: note: ‘ll’ was not declared ‘constexpr’
     ll n, ans = 1;
     ^
./Main.cpp:12:14: error: type/value mismatch at argument 1 in template parameter list for ‘template<class _Tp, class _Alloc> class std::vector’
     vector<ll> a(n);
              ^
./Main.cpp:12:14: note:   expected a type, got ‘ll’
./Main.cpp:12:14: error: template argument 2 is invalid
./Main.cpp:13:13: error: expected ‘;’ before ‘i’
     for (ll i = 0; i < n; ++i) cin >> a.at(i);
             ^
./Main.cpp:13:20: error: ‘i’ was not declared in this scope
     for (ll i = 0; i < n; ++i) cin >> a.at(i);
                    ^
./Main.cpp:13:41: error: request for member ‘at’ in ‘a’, which is of ...