1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
#include <bits/stdc++.h>
#define mod 1000000007
using namespace std;

long long a[300000], dp[300000];

int main()
{
	ios_base::sync_with_stdio(0);
	cin.tie(0);
	
	int n;
	cin >> n;
	
	for(int i = 0; i < n; ++i) cin >> a[i];
	
	if(n <= 3000)
	{
		for(int i = 0; i < n; ++i)
		{
			long long sum = 0;
			for(int j = i; j >= 0; --j)
			{
				sum += a[j];
				sum %= mod;
				
				if(sum%2 == 0)
				{
					if(j) dp[i] += dp[j-1];
					else dp[i] += 1;
					
					dp[i] %= mod;
				}
			}
		}
		
		cout << dp[n-1];
		
		return 0;
	}
	
	long long wyn = 1;
	int sum = 0;
	for(int i = 0; i < n-1; ++i)
	{
		sum += a[i]%2;
		if(sum%2 == 0)
		{
			wyn <<= 1;
			wyn %= mod;
		}
	}
	sum += a[n-1];
	
	if(sum%2 == 0) cout << wyn;
	else cout << 0;

	return 0;
}