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94-Binary-Tree-Inorder-Traversal

问题描述

Given the root of a binary tree, return the inorder traversal of its nodes’ values.

解题思路

  • 代码如下:

  • JavaScript

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/**
* 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 inorderTraversal = function(root) {
if (!root) return [];

var res = [];
var stack = [];

while (stack.length || root) {
if (root) {
stack.push(root);
root = root.left;
} else {
root = stack.pop();
res.push(root.val);
root = root.right;
}
}

return res;
};
  • 时间复杂度:O(n)
  • 空间复杂度:O(n)