【贪心】时空定位II 区间覆盖

#include <bits/stdc++.h>

using namespace std;
const int maxn = 605;
struct uct {
    double left, right;
};
bool cmp(uct a, uct b) {
    if(a.left == b.left) {
        return a.right > b.right;
    }
    return a.left < b.left;
}

int main() {
    ios::sync_with_stdio(false);
    uct s[maxn];
    int n, t;
    cin >> t;
    while(t--) {
        double r, w, h, x;
        cin >> n >> w >> h;
        h = h*1.0/2;
        for(int i = 0; i < n; i++) {
            cin >> x >> r;
            if(r > h) {
                double y = r*r - h*h;
                s[i].left =  max(x - sqrt(y), 0.0);
                s[i].right = min(x + sqrt(y), w);
            } else {
                s[i].left = x;
                s[i].right = x;
            }
        }
        sort(s, s+n, cmp);
        int cnt = 0;
        double start = 0;
        int i = -1;
        while(start < w && s[i+1].left <= start) {
            double MAX = -1;
            for(int j = i + 1; s[j].left <= start && j < n; j++) {
               if(MAX < s[j].right){
                MAX =  s[j].right;
                i = j;
               }
            }
            start  = MAX;
            cnt++;
        }
        if(start >= w) cout << cnt << endl;
        else cout << 0 << endl;
    }
    return 0;
}