南阳理工12题

#include<iostream>#include<vector>#include<algorithm>#include<cmath>using namespace std;double r, x, y, width, height;class Circle{public:Circle(double x, double r) :x(x), r(r){}double Left() const{if (r*r - height*height / 4<0) return x; return x - sqrt(r*r - (height*height / 4));}double Right() const{ if (r*r - height*height / 4<0) return x; return x + sqrt(r*r - (height*height / 4)); }friend ostream & operator<<(ostream& out, const Circle& circle);private:double x, r;};ostream & operator<<(ostream& out, const Circle& circle){out << circle.x << " " << circle.r;return out;}struct CircleLess{bool operator()(const Circle& c1, const Circle& c2){return c1.Right()<c2.Right();}};int main(){int m;cin >> m;while (m--){int n;vector<Circle> Rs;cin >> n >> width >> height;Rs.reserve(n);while (n--){cin >> x >> r;Rs.push_back(Circle(x, r));}sort(Rs.begin(), Rs.end(), CircleLess());vector<int> choosed;choosed.push_back(-1);double len = 0;try{while (len<width){int last = -1;for (vector<Circle>::size_type i = choosed.back() + 1; i != Rs.size(); i++){if (Rs[i].Left() <= len){//cout<<Rs[i].Left()<<endl;last = i;}}if (last == -1) throw - 1;else{choosed.push_back(last);len = Rs[last].Right();}}cout << choosed.size() - 1 << endl;}catch (...){cout << 0 << endl;}}}