#include <iostream>
using namespace std;
const int SIZE = 300001,
DIV = 1000000007;
int n, c;
int arr[SIZE],
dp[SIZE];
int combs(int id = 1, int val = arr[1]) {
if(id == n) {
if((val % DIV) % 2 == 0)
return 1;
else
return 0;
}
if((val % DIV) % 2 == 0) {
if(dp[id + 1] == -1)
dp[id + 1] = combs(id + 1, arr[id + 1] % DIV);
return dp[id + 1] + combs(id + 1, (val + arr[id + 1]) % DIV);
}
else
return combs(id + 1, (val + arr[id + 1]) % DIV);
}
int main() {
cin >> n;
for(int i = 1; i <= n; i++)
cin >> arr[i];
for(int i = 0; i <= n; i++) dp[i] = -1;
cout << combs() << "\n";
}
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 | #include <iostream> using namespace std; const int SIZE = 300001, DIV = 1000000007; int n, c; int arr[SIZE], dp[SIZE]; int combs(int id = 1, int val = arr[1]) { if(id == n) { if((val % DIV) % 2 == 0) return 1; else return 0; } if((val % DIV) % 2 == 0) { if(dp[id + 1] == -1) dp[id + 1] = combs(id + 1, arr[id + 1] % DIV); return dp[id + 1] + combs(id + 1, (val + arr[id + 1]) % DIV); } else return combs(id + 1, (val + arr[id + 1]) % DIV); } int main() { cin >> n; for(int i = 1; i <= n; i++) cin >> arr[i]; for(int i = 0; i <= n; i++) dp[i] = -1; cout << combs() << "\n"; } |
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