Valid Arrangement of Pairs
You are given a 0-indexed 2D integer array pairs where pairs[i] = [starti, endi]. An arrangement of pairs is valid if for every index i where 1 <= i < pairs.length, we have endi-1 == starti.
Return any valid arrangement of pairs.
Note: The inputs will be generated such that there exists a valid arrangement of pairs.
Example 1
Input
pairs = [[5,1],[4,5],[11,9],[9,4]]Output
[[11,9],[9,4],[4,5],[5,1]]This is a valid arrangement since each pair's end equals the next pair's start:
9 == 9, 4 == 4, and 5 == 5.Example 2
Input
pairs = [[1,3],[3,2],[2,1]]Output
[[1,3],[3,2],[2,1]]This is a valid arrangement since each pair's end equals the next pair's start, and other cyclic rotations are also valid.
Constraints
- 1 <= pairs.length <= 10^5
- pairs[i].length == 2
- 0 <= starti, endi <= 10^9
- starti != endi
- No two pairs are exactly the same.
- There exists a valid arrangement of pairs.