# POJ1328

Written by    00:17 July 10, 2014

 Time Limit: 1000MS Memory Limit: 10000K Total Submissions: 66695 Accepted: 14946

Description

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

Input

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

Output

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.

Sample Input

Sample Output

Source

2 5

-3 4

-6 3

4 5

-5 3

-3 5

2 3

3 3

20 8

-20 7

-18 6

-5 8

-21 8

-15 7

-17 5

-1 5

-2 3

-9 6

1 2

2 3

3 4

4 5

5 6

6 7

7 8

8 7

9 6

10 5

0 0

2 3

0 2

2 3

2 3

0 2

1 3

3 3

1 2

-3 2

2 4

8 5

2 4

-4 4

-3 3

-3 1

-3 0

-1 0

0 5

6 0

3 0

1 2

-3 1

2 1

3 2

1 2

-3 1

2 1

1 2

0 2

2 3

0 2

2 3

4 -5

4 3

4 3

2 3

6 -9

3 -3

1 2

-3 2

2 1

6 2

1 2

1 2

1 2

-3 1

2 1

0 0

1 2

0 2

2 3

0 2

1 3

3 10

1 10

2 3

4 5

3 5

1 10

2 3

4 5

4 7

1 10

2 3

4 5

0 0

3 9

1 10

2 3

4 5

0 0

================结果

Case 1: 1

Case 2: 2

Case 3: 4

Case 4: 1

Case 5: 1

Case 6: -1

Case 7: 3

Case 8: -1

Case 9: 2

Case 10: 1

Case 11: 1

Case 12: -1

Case 13: -1

Case 14: 2

Case 15: 1

Case 16: 1

Case 17: 1

Case 18: -1

Case 19: -1

Case 20: -1

d<=0不需要判断

y<=0 不需要判断

Category : acmstudy

Tags :