Find Original Array From Doubled Array

arrayhash tablegreedy

Problem Statement

An integer array original is transformed into a doubled array changed by appending twice the value of every element in original , and then randomly shuffling the resulting array.

Given an array changed , return original if changed is a doubled array. If changed is not a doubled array, return an empty array. The elements in original may be returned in any order .

Examples

Example 1

Input: changed = [1,3,4,2,6,8]
Output: [1,3,4]
One possible original array could be [1,3,4]:
- Twice the value of 1 is 1 * 2 = 2.
- Twice the value of 3 is 3 * 2 = 6.
- Twice the value of 4 is 4 * 2 = 8.
Other original arrays could be [4,3,1] or [3,1,4].

Example 2

Input: changed = [6,3,0,1]
Output: []
changed is not a doubled array.

Example 3

Input: changed = [1]
Output: []
changed is not a doubled array.

Constraints

1 <= changed.length <= 10 ^5

0 <= changed[i] <= 10 ^5

🤔

Medium

Difficulty

Topic Info

ModuleDSA

CategoryArray

Sub-topicHash Table