Counting SCCs ?

Revision en4, by bao987, 2025-08-08 11:30:55

We are given $$$n$$$ points $$$(x_i, y_i)$$$, each with a transmission radius $$$r_i$$$. If a point already has the signal, it will transmit the signal to another point if:

$$$ (x_i - x_j)^2 + (y_i - y_j)^2 \le r_i^2 $$$

or

$$$ (x_i - x_j)^2 + (y_i - y_j)^2 \le r_j^2 $$$

Once a point receives the signal, it will also start transmitting according to the same rule.

Task: Find the minimum number of points that must be directly connected to the signal so that, starting from these initially connected points, all $$$n$$$ points will eventually receive the signal. Example:

3

1 0 1

2 0 1

5 0 1

Output:


2

History

 
 
 
 
Revisions
 
 
  Rev. Lang. By When Δ Comment
en7 English bao987 2025-08-09 08:00:46 60
en6 English bao987 2025-08-08 12:57:26 78
en5 English bao987 2025-08-08 11:32:12 199
en4 English bao987 2025-08-08 11:30:55 2 Tiny change: 'me rule.\n**Task:*' -> 'me rule.\n\n**Task:*'
en3 English bao987 2025-08-08 11:30:28 12 Tiny change: 'utput:**\n```\n2\n```\n' -> 'utput:**\n\n```\n\n2\n\n```\n'
en2 English bao987 2025-08-08 11:29:47 6 Tiny change: '\n```\n3\n1 0 1\n2 0 1\n5 0 1\n`' -> '\n```\n3\n\n1 0 1\n\n2 0 1\n\n5 0 1\n`'
en1 English bao987 2025-08-08 11:29:29 654 Initial revision (published)