#include <bits/stdc++.h>
using namespace std;
constexpr int MAXN=3e5+7, MOD=1e9+7;
int mozliwosci[MAXN], pref[MAXN];
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
int n, a;
cin >> n;
pref[0] = 0;
for (int i=1; i <= n; i++) {
cin >> a;
pref[i] = pref[i-1] + a;
pref[i] %= MOD;
}
for (int i=1; i <= n; i++) {
if ((pref[i] & 1) == 0) {
mozliwosci[i]++;
mozliwosci[i] %= MOD;
}
for (int j=1; j < i; j++) {
if ((((pref[i] - pref[j] + MOD) % MOD) & 1) == 0) {
mozliwosci[i] += mozliwosci[j];
mozliwosci[i] %= MOD;
}
}
}
cout << mozliwosci[n];
return 0;
}
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 | #include <bits/stdc++.h> using namespace std; constexpr int MAXN=3e5+7, MOD=1e9+7; int mozliwosci[MAXN], pref[MAXN]; int main() { ios_base::sync_with_stdio(false); cin.tie(nullptr); int n, a; cin >> n; pref[0] = 0; for (int i=1; i <= n; i++) { cin >> a; pref[i] = pref[i-1] + a; pref[i] %= MOD; } for (int i=1; i <= n; i++) { if ((pref[i] & 1) == 0) { mozliwosci[i]++; mozliwosci[i] %= MOD; } for (int j=1; j < i; j++) { if ((((pref[i] - pref[j] + MOD) % MOD) & 1) == 0) { mozliwosci[i] += mozliwosci[j]; mozliwosci[i] %= MOD; } } } cout << mozliwosci[n]; return 0; } |
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