1、贪心算法，刚开始不知道哪里搞错了，总是超时....
1 #include<cstdio> 2 #include<algorithm> 3 #include<cstring> 4 #include<queue> 5 #include<math.h> 6 #include <iostream> 7 #include <string> 8 #include <vector> 9 #include <cstdlib> 10 #include <cmath> 11 #include <map> 12 #include <list> 13 #include <ctime> 14 #include <queue> 15 #include <stdlib.h> 16 using namespace std; 17 18 struct range { 19 double l, r; 20 }; 21 22 bool comp(const range &A, const range &B) { 23 if (A.r < B.r) { 24 return true; 25 } else if (A.r == B.r) { 26 return A.l < B.l; 27 } else { 28 return false; 29 } 30 } 31 32 int main() { 33 int n, d, ans, flag; 34 int ct = 1; 35 while (1) { 36 vector<range> data; 37 cin >> n >> d; 38 if (0 == d && 0 == n) 39 break; 40 ans = 1; 41 flag = 1; 42 if (d < 0) 43 flag = 0; 44 for (int i = 0; i < n; i++) { 45 int x, y; 46 cin >> x >> y; 47 double t; 48 t = sqrt(((double) d * d - (double) y * y)); 49 range tk; 50 tk.l = (double) x - t; 51 tk.r = (double) x + t; 52 data.push_back(tk); 53 if (y > d || (-y) > d) 54 flag = 0; 55 } 56 if (flag == 0) 57 ans = -1; 58 else { 59 if (0 == n) 60 ans = 0; 61 else { 62 sort(data.begin(), data.end(), comp); 63 double left = data[0].r; 64 for (int i = 1; i < n; i++) { 65 if (data[i].l > left) { 66 ans++; 67 left = data[i].r; 68 } 69 } 70 } 71 } 72 cout << "Case " << ct << ": " << ans << endl; 73 ct++; 74 } 75 return 0; 76 }