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OI-codes/Luogu/P2717/P2717.cpp

57 lines
935 B
C++

#include <iostream>
#include <algorithm>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 1e5 + 5;
int n, k, a[N], b[N];
long long ans;
void solve(int l, int r) {
if (l == r) {
if (a[l] >= 0) ans++;
return;
}
int mid = l + r >> 1;
solve(l, mid);
solve(mid + 1, r);
b[mid] = a[mid];
for (int i = mid - 1; i >= l; i--) b[i] = b[i + 1] + a[i];
std::sort(b + l, b + mid + 1);
b[mid + 1] = a[mid + 1];
for (int i = mid + 2; i <= r; i++) b[i] = b[i - 1] + a[i];
std::sort(b + mid + 1, b + r + 1);
int i = l, j = r;
while (i <= mid) {
while (j > mid && b[i] + b[j] >= 0) j--;
ans += r - j;
i++;
}
}
int main() {
std::ios::sync_with_stdio(false);
cin >> n >> k;
for (int i = 1; i <= n; i++) {
cin >> a[i];
a[i] -= k;
}
solve(1, n);
cout << ans << endl;
return 0;
}