LeetCode145. Binary Tree Postorder Traversal

Binary Tree Postorder Traversal"/>

LeetCode145. Binary Tree Postorder Traversal

文章目录

• • 一、题目
  • 二、题解

一、题目

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

Example 1:

Input: root = [1,null,2,3]
Output: [3,2,1]
Example 2:

Input: root = []
Output: []
Example 3:

Input: root = [1]
Output: [1]

Constraints:

The number of the nodes in the tree is in the range [0, 100].
-100 <= Node.val <= 100

Follow up: Recursive solution is trivial, could you do it iteratively?

二、题解

/*** Definition for a binary tree node.* struct TreeNode {*     int val;*     TreeNode *left;*     TreeNode *right;*     TreeNode() : val(0), left(nullptr), right(nullptr) {}*     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}*     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}* };*/
class Solution {
public:void postOrder(TreeNode* root,vector<int>& res){if(root == nullptr) return;postOrder(root->left,res);postOrder(root->right,res);res.push_back(root->val);}vector<int> postorderTraversal(TreeNode* root) {vector<int> res;postOrder(root,res);return res;}
};