Group Meetings (APCS 2025-01 Expert)

2.0s 256M

There are \(n\) people at positions \(x_i\) on a line. Choose two disjoint groups of \(k\) people each. Each group chooses a meeting point; its members pay their distances to it. Minimize the total distance.

Input Format

Read \(n,k\), then the \(n\) positions.

Output Format

Print the minimum total distance.

Constraints

\(1\le k\), \(2k\le n\le200000\); \(0\le x_i\le10^9\). Positions may repeat.

Scoring

  • 30 points: \(n\le100\).
  • 70 points: No additional restrictions.

Each scored test is worth 5 points.

Sample Input 1

6 2
5 2 0 6 9 6

Sample Output 1

2

Sample Input 2

7 3
6 3 2 2 0 9 8

Sample Output 2

4

Source

APCS 2025-01 public archive version: q184。

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