- 总时间限制:
- 1000ms
- 内存限制:
- 65536kB

- 描述
- Assume the coasting is an infinite straight line. Land is in one side of coasting, sea in the other. Each small island is a point locating in the sea side. And any radar installation, locating on the coasting, can only cover d distance, so an island in the sea can be covered by a radius installation, if the distance between them is at most d.

We use Cartesian coordinate system, defining the coasting is the x-axis. The sea side is above x-axis, and the land side below. Given the position of each island in the sea, and given the distance of the coverage of the radar installation, your task is to write a program to find the minimal number of radar installations to cover all the islands. Note that the position of an island is represented by its x-y coordinates.

Figure A Sample Input of Radar Installations - 输入
- The input consists of several test cases. The first line of each case contains two integers n (1<=n<=1000) and d, where n is the number of islands in the sea and d is the distance of coverage of the radar installation. This is followed by n lines each containing two integers representing the coordinate of the position of each island. Then a blank line follows to separate the cases.

The input is terminated by a line containing pair of zeros - 输出
- For each test case output one line consisting of the test case number followed by the minimal number of radar installations needed. "-1" installation means no solution for that case.
- 样例输入
3 2 1 2 -3 1 2 1 1 2 0 2 0 0

- 样例输出
Case 1: 2 Case 2: 1

- 来源
- Beijing 2002

- 全局题号
- 330
- 添加于
- 2009-10-29
- 提交次数
- 2628
- 尝试人数
- 460
- 通过人数
- 363

9.1%

63.6%

9.1%

9.1%