Problem:
Score : 300 points

Problem Statement

A sequence a_1,a_2,... ,a_n is said to be /\/\/\/ when the following conditions are satisfied:

For each i = 1,2,..., n-2, a_i = a_{i+2}.

Exactly two different numbers appear in the sequence.

You are given a sequence v_1,v_2,...,v_n whose length is even.
We would like to make this sequence /\/\/\/ by replacing some of its elements.
Find the minimum number of elements that needs to be replaced.

Constraints

2 \leq n \leq 10^5

n is even.

1 \leq v_i \leq 10^5

v_i is an integer.

Input

Input is given from Standard Input in the following format:

n
v_1 v_2 ... v_n

Output

Print the minimum number of elements that needs to be replaced.

Sample Input 1

4
3 1 3 2

Sample Output 1

1

The sequence 3,1,3,2 is not /\/\/\/, but we can make it /\/\/\/ by replacing one of its elements: for example, replace the fourth element to make it 3,1,3,1.

Sample Input 2

6
105 119 105 119 105 119

Sample Output 2

0

The sequence 105,119,105,119,105,119 is /\/\/\/.

Sample Input 3

4
1 1 1 1

Sample Output 3

2

The elements of the sequence 1,1,1,1 are all the same, so it is not /\/\/\/.

Solution in Scala (2.11.7) (judge verdict: Accepted)


import java.util.Scanner

object Main extends App {

  val sc = new Scanner(System.in)

  val n = sc.nextInt()
  val ar0 = Array.fill(n / 2)(0)
  val ar1 = Array.fill(n / 2)(0)
  val map = Range(0, n).map((_, sc.nextInt()))
    .map(t => if (t._1 % 2 == 0) ar0(t._1 / 2) = t._2 else ar1(t._1 / 2) = t._2)

  val or0 = ar0.toSeq.groupBy(i => i)
    .map(t => (t._1, t._2.length))
    .toSeq.sortBy(_._2).reverse

  val or1 = ar1.toSeq.groupBy(i => i)
    .map(t => (t._1, t._2.length))
    .toSeq.sortBy(_._2).reverse

  if (or0(0)._1 == or1(0)._1) {
    if (or0.length == 1) {
      if (or1.length == 1) {
        println(n / 2)
      } else {
        println(n / 2 - or1(1)._2)
      }
    } else {
      if (or1.length == 1) {
        println(n / 2 - or0(1)._2)
      } else {
        println(math.min(n - or1(0)._2 - or0(1)._2, n - or1(1)._2 - or0(0)._2))
      }
    }
  } else {
    val ans = n - or0(0)._2 - or1(0)._2
    println(ans)
  }

}