Binary Tree Zigzag Level Order Traversal LeetCode (ZigZag Tree Traversal)

Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between).

For example:
Given binary tree {3,9,20,#,#,15,7},

    3
   / \
  9  20
    /  \
   15   7

return its zigzag level order traversal as:

[
  [3],
  [20,9],
  [15,7]
]

confused what "{1,#,2,3}" means? > read more on how binary tree is serialized on OJ.

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Solution Source: Java

	/**
	Given a binary tree, return the zigzag level order traversal of its nodes' values. (ie, from left to right, then right to left for the next level and alternate between).
	For example:
	Given binary tree [3,9,20,null,null,15,7],
	3
	/ \
	9 20
	/ \
	15 7
	return its zigzag level order traversal as:
	[
	[3],
	[20,9],
	[15,7]
	]
	*/
	class TreeNode {
	int val;
	TreeNode left;
	TreeNode right;
	TreeNode(int x) { val = x; }
	}
	public class BinaryTreeZigzagLevelOrder{
	public List<List<Integer>> zigzagLevelOrder(TreeNode root) {
	}
	public static void main(String[] args){
	}
	}

view raw BinaryTreeZigzagLevelOrder.java hosted with ❤ by GitHub