Open Tcdian opened 4 years ago
/**
* Definition for a binary tree node.
* function TreeNode(val, left, right) {
* this.val = (val===undefined ? 0 : val)
* this.left = (left===undefined ? null : left)
* this.right = (right===undefined ? null : right)
* }
*/
/**
* @param {TreeNode} root
* @return {number[][]}
*/
var zigzagLevelOrder = function(root) {
if (root === null) {
return [];
}
const result = [];
const queue = [[root, 0]];
while(queue.length !== 0) {
const [node, level] = queue.shift();
result[level] = result[level] || [];
if (level % 2 === 0) {
result[level].push(node.val);
} else {
result[level].unshift(node.val);
}
if (node.left !== null) {
queue.push([node.left, level + 1]);
}
if (node.right !== null) {
queue.push([node.right, level + 1]);
}
}
return result;
};
/**
* Definition for a binary tree node.
* class TreeNode {
* val: number
* left: TreeNode | null
* right: TreeNode | null
* constructor(val?: number, left?: TreeNode | null, right?: TreeNode | null) {
* this.val = (val===undefined ? 0 : val)
* this.left = (left===undefined ? null : left)
* this.right = (right===undefined ? null : right)
* }
* }
*/
function zigzagLevelOrder(root: TreeNode | null): number[][] {
if (root === null) {
return [];
}
const result: number[][] = [];
const queue: [TreeNode, number][] = [[root, 0]];
while(queue.length !== 0) {
const [node, level] = queue.shift() as [TreeNode, number];
result[level] = result[level] || [];
if (level % 2 === 0) {
result[level].push(node.val);
} else {
result[level].unshift(node.val);
}
if (node.left !== null) {
queue.push([node.left, level + 1]);
}
if (node.right !== null) {
queue.push([node.right, level + 1]);
}
}
return result;
};
103. Binary Tree Zigzag Level Order Traversal
给定一个二叉树,返回其节点值的锯齿形层次遍历。(即先从左往右,再从右往左进行下一层遍历,以此类推,层与层之间交替进行)。
Example
给定二叉树
[3,9,20,null,null,15,7]
:return its zigzag level order traversal as: