题解 | 小红的数组

#include <bits/stdc++.h>
#define int long long
using namespace std;
int n, k, a[300005], ans1, ans2, ans3, l1, l2;
signed main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cin >> n >> k;
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    sort(a, a + n);
    for (int i = n - 1; i > -1; i--) {
        l1 = min(l1, i);
        l2 = min(l2, i);
        while (l1 < i && a[l1] * a[i] < k) {
            l1++;
        }
        while (l2 < i && a[l2] * a[i] <= k) {
            l2++;
        }
        ans1 += i - l2;
        ans2 += l2 - l1;
        ans3 += l1;
    }
    cout << ans1 << " " << ans2 << " " << ans3;
    return 0;
}