Submission #1244171

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Source Code Expand

#include <iostream>
#include <cmath>
#include <algorithm>
using namespace std;
typedef long long int ll;
#define MOD (1000000007);
#define INF (2e9)



int main(void) {
    int n;
    cin >> n;
    int *a = new int[n];
    for (int i = 0; i<n; i++) {
        cin >> a[i];
    }
    sort(a, a + n);

    for (int i = 0; i<n; i++) {
        if (a[i] != (n % 2 == 0 ? i / 2 * 2 + 1 : (i + 1) / 2 * 2)) {
            cout << 0 << endl;
            return 0;
        }
    }
    ll ans = 1;
    for (int i = 0; i<n / 2; i++) {
        ans = (ans * 2) % MOD;
    }
    cout << ans << endl;
    delete(a);
    return 0;
}

Submission Info

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