Given an n-ary tree, return the level order traversal of its nodes’ values. (ie, from left to right, level by level).
For example, given a 3-ary tree:
We should return its level order traversal:
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[ [1], [3,2,4], [5,6] ]
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Note
- The depth of the tree is at most 1000.
- The total number of nodes is at most 5000.
Code
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public class { public int val; public List<Node> children; public (int _val, List<Node> _children) { val = _val; children = _children; } }
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public List<List<Integer>> levelOrder(Node root) { List<List<Integer>> result = new ArrayList<>();
if (root == null) return result;
Queue<Node> queue = new LinkedList<>(); queue.offer(root);
while (!queue.isEmpty()) { int size = queue.size(); List<Integer> nodes = new ArrayList<>();
for (int i = 0; i < size; i++) { Node node = queue.poll(); nodes.add(node.val); List<Node> children = node.children;
if (children != null) { for (Node child : children) queue.offer(child); } }
result.add(nodes); }
return result; }
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