Leetcode 429. N-ary Tree Level Order Traversal

Input: root = [1,null,3,2,4,null,5,6]
Output: [[1],[3,2,4],[5,6]]
Input: root = [1,null,2,3,4,5,null,null,6,7,null,8,null,9,10,null,null,11,null,12,null,13,null,null,14]
Output: [[1],[2,3,4,5],[6,7,8,9,10],[11,12,13],[14]]
  • The height of the n-ary tree is less than or equal to 1000
  • The total number of nodes is between [0, 104]
  1. create List<List<Integer>> for the result
  2. if root == null, return result
  3. create Queue<Node> queue as LinkedList, offer the root in queue
  4. while queue is not empty, create another new list, poll all the node in queue, add them into the current list, at the same time, add node.children into the queue -> first in first out -> so we have to know queue size in the first place
  5. result add current list and check it again until queue is empty
  6. return result

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Gary Chiang

Gary Chiang

CS new grad, 6 years experience related to supply chain management. Located in Bay area