Open Tcdian opened 3 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 postorderTraversal = function(root) {
if (root === null) {
return [];
}
const queue = [];
let patrol = root;
const result = [];
while (patrol !== null || queue.length !== 0) {
while (patrol !== null) {
queue.push([patrol, 0]);
patrol = patrol.left;
}
let pair = queue.pop();
if (pair[1] === 1) {
result.push(pair[0].val);
} else {
pair[1] += 1;
queue.push(pair);
patrol = pair[0].right;
}
}
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 postorderTraversal(root: TreeNode | null): number[] {
if (root === null) {
return [];
}
const queue: [TreeNode, number][] = [];
let patrol: TreeNode | null = root;
const result: number[] = [];
while (patrol !== null || queue.length !== 0) {
while (patrol !== null) {
queue.push([patrol, 0]);
patrol = patrol.left;
}
let pair = queue.pop()!;
if (pair[1] === 1) {
result.push(pair[0].val);
} else {
pair[1] += 1;
queue.push(pair);
patrol = pair[0].right;
}
}
return result;
};
145. Binary Tree Postorder Traversal
给定一个二叉树,返回它的 后序 遍历。
Example 1
Example 2
Example 3
Example 4
Example 5
Note
[0, 100]
.-100 <= Node.val <= 100