是模拟，过了两个点，时间上没什么大问题

#include <bits/stdc++.h>
using namespace std;
const int N = 50005;
struct cow {
    int x;
    int h;
};
cow c[N];
bool cmp(cow a, cow b) {
    return a.h > b. h;
}
int n, d, ans = 0;
int main() {
    cin >> n >> d;
    int i = n + 1, j;
    while(--i != 0) cin >> c[n - i].x >> c[n - i].h;
    sort(c, c + n, cmp);
    for(i = n - 1; i >= 0; i--) {
        for(j = i - 1; j >= 0; j--) {
            if(abs(c[i].x - c[j].x) <= d&&c[j].h / 2 >= c[i].h) {ans++; break;}
        }
    }
    cout << ans / 2 << endl;
	return 0;
}