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

Input Format

The first argument is an integer array A.
The first argument is an integer array A.

Output Format

Return an array arranged in the sequence as described.
Return an array arranged in the sequence as described.

Example Input

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

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

Input 2:
A = [1, 2]

Example Output

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

Output 2:
[2, 1]
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].
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
	}
}
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 ​