Array of Doubled Pairs(LeetCode 954):

Problem

Given an integer array of even length arr, return true if it is possible to reorder arr such that arr[2 * i + 1] = 2 * arr[2 * i] for every 0 <= i < len(arr) / 2, or false otherwise.

 

Example 1:

Input: arr = [3,1,3,6]
Output: false

Example 2:

Input: arr = [2,1,2,6]
Output: false

Example 3:

Input: arr = [4,-2,2,-4]
Output: true
Explanation: We can take two groups, [-2,-4] and [2,4] to form [-2,-4,2,4] or [2,4,-2,-4].

 

Constraints:

  • 2 <= arr.length <= 3 * 104
  • arr.length is even.
  • -105 <= arr[i] <= 105