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#include <cstdio> #include <cstring> #include <algorithm> #include <cstdlib> #include <string> #include <vector> using namespace std;
typedef long long LL; const int maxn = (1 << 20) + 10; int sum[maxn];
int main() { freopen("subset.in", "r", stdin); freopen("subset.out", "w", stdout); int n; scanf("%d", &n); int aim = (n * (n + 1)) >> 1; if (aim & 1) { puts("0"); return 0; } aim >>= 1; int p = (n + 1) >> 1, S = 1 << p, num = S; for (int i = 0; i < S; ++i) { for (int j = 0; j < p; ++j) { if (i & (1 << j)) { sum[i] += j + 1; } } } sort(sum, sum + num); p = n - p, S = 1 << p; LL ans = 0; for (int i = 0; i < S; ++i) { int tmp = 0; for (int j = 0; j < p; ++j) { if (i & (1 << j)) { tmp += n - j; } } ans += int(upper_bound(sum, sum + num, aim - tmp) - lower_bound(sum, sum + num, aim - tmp)); } printf("%d\n", int(ans >> 1)); return 0; }
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