提出 #7032002

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ソースコード 拡げる

#include<iostream>
#include<vector>
#include<string>
#include<cstring>
#include<algorithm>
#include<map>
#include<set>
#include<cmath>
#include<cassert>
#include<queue>

using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef vector<int> vi;
struct cww {
    cww() {
        ios::sync_with_stdio(false);
        cin.tie(0);
    }
} star;

const int MAXN = 100100;
const int MOD = 1e9+7;
int cnt[MAXN];

int solve(int N) {
    ll ans = 1;
    if (N % 2 == 1) {
        if (cnt[0] != 1)
            return 0;
        for (int i = 2; i < N; i += 2) {
            if (cnt[i] != 2)
                return 0;

            ans*=2;
            ans%= MOD;
        }
        return ans;
    } else {
        for (int i = 1; i < N; i+=2) {
            if (cnt[i] != 2)
                return 0;

            ans*=2;
            ans%=MOD;
        }
        return ans;
    }
}

int main() {
    int N;
    cin >> N;
    for (int i = 0; i < N; i++) {
        int a;
        cin >> a;
        cnt[a]++;
    }
    cout << solve(N) << endl;
    return 0;
}

提出情報

ジャッジ結果