102. Binary Tree Level Order Traversal
Description
Given a binary tree, return the level order traversal of its nodes' values. (i.e, from left to right, level by level).
Constraints
Approach
Links
YouTube
Examples
Input: [3, 9, 20, null, null, 15, 7]

Output:
[
[3],
[9, 20],
[15, 7]
]
Solutions
// Definition for a binary tree node.
public class TreeNode {
int val;
TreeNode left;
TreeNode right;
TreeNode() {}
TreeNode(int val) { this.val = val; }
TreeNode(int val, TreeNode left, TreeNode right) {
this.val = val;
this.left = left;
this.right = right;
}
}
Follow up
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