1743. Restore the Array From Adjacent Pairs

https://leetcode.com/problems/restore-the-array-from-adjacent-pairs

Description

There is an integer array nums that consists of n unique elements, but you have forgotten it. However, you do remember every pair of adjacent elements in nums.

You are given a 2D integer array adjacentPairs of size n - 1 where each adjacentPairs[i] = [ui, vi] indicates that the elements ui and vi are adjacent in nums.

It is guaranteed that every adjacent pair of elements nums[i] and nums[i+1] will exist in adjacentPairs, either as [nums[i], nums[i+1]] or [nums[i+1], nums[i]]. The pairs can appear in any order.

Return the original array nums. If there are multiple solutions, return any of them.

Example 1:

**Input:** adjacentPairs = [[2,1],[3,4],[3,2]]
**Output:** [1,2,3,4]
**Explanation:** This array has all its adjacent pairs in adjacentPairs.
Notice that adjacentPairs[i] may not be in left-to-right order.

Example 2:

**Input:** adjacentPairs = [[4,-2],[1,4],[-3,1]]
**Output:** [-2,4,1,-3]
**Explanation:** There can be negative numbers.
Another solution is [-3,1,4,-2], which would also be accepted.

Example 3:

**Input:** adjacentPairs = [[100000,-100000]]
**Output:** [100000,-100000]

Constraints:

• nums.length == n

• adjacentPairs.length == n - 1

• adjacentPairs[i].length == 2

• 2 <= n <= 105

• -105 <= nums[i], ui, vi <= 105

• There exists some nums that has adjacentPairs as its pairs.

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