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Wave Array ​

Problem Description ​

Given an array of integers A, sort the array into a wave-like array and return it. In other words, arrange the elements into a sequence such that

a1 >= a2 <= a3 >= a4 <= a5.....

NOTE: If multiple answers are possible, return the lexicographically smallest one.

Problem Constraints

1 <= len(A) <= 10^6
1 <= A[i] <= 10^6

Input Format

The first argument is an integer array A.

Output Format

Return an array arranged in the sequence as described.

Example Input

Input 1:
A = [1, 2, 3, 4]

Input 2:
A = [1, 2]

Example Output

Output 1:
[2, 1, 4, 3]

Output 2:
[2, 1]

Example Explanation

Explanation 1:
One possible answer : [2, 1, 4, 3]
Another possible answer : [4, 1, 3, 2]
First answer is lexicographically smallest. So, return [2, 1, 4, 3].

Explanation 2:

Only possible answer is [2, 1].

Solution ​

swift
import Foundation

class Solution {
	func wave(_ A: inout [Int]) -> [Int] {
        var B = A.sorted() 
        for i in 0..<(B.count/2){
            let tmp = B[2*i+1]
            B[2*i+1] = B[2*i]
            B[2*i] = tmp
        }
        return B
	}
}

References ​