poj 1328

1、贪心算法，刚开始不知道哪里搞错了，总是超时....

#include<cstdio>
#include<algorithm>
#include<cstring>
#include<queue>
#include<math.h>
#include <iostream>
#include <string>
#include <vector>
#include <cstdlib>
#include <cmath>
#include <map>
#include <list>
#include <ctime>
#include <queue>
#include <stdlib.h>
using namespace std;

struct range {
    double l, r;
};

bool comp(const range &A, const range &B) {
    if (A.r < B.r) {
        return true;
    } else if (A.r == B.r) {
        return A.l < B.l;
    } else {
        return false;
    }
}

int main() {
    int n, d, ans, flag;
    int ct = 1;
    while (1) {
        vector<range> data;
        cin >> n >> d;
        if (0 == d && 0 == n)
            break;
        ans = 1;
        flag = 1;
        if (d < 0)
            flag = 0;
        for (int i = 0; i < n; i++) {
            int x, y;
            cin >> x >> y;
            double t;
            t = sqrt(((double) d * d - (double) y * y));
            range tk;
            tk.l = (double) x - t;
            tk.r = (double) x + t;
            data.push_back(tk);
            if (y > d || (-y) > d)
                flag = 0;
        }
        if (flag == 0)
            ans = -1;
        else {
            if (0 == n)
                ans = 0;
            else {
                sort(data.begin(), data.end(), comp);
                double left = data[0].r;
                for (int i = 1; i < n; i++) {
                    if (data[i].l > left) {
                        ans++;
                        left = data[i].r;
                    }
                }
            }
        }
        cout << "Case " << ct << ": " << ans << endl;
        ct++;
    }
    return 0;
}