二叉树的后序遍历

一.题目描述

给出一棵二叉树，返回其节点值的后序遍历。

样例

{1,#,2,3}

1
\
2
/
3

[3,2,1]

三.实现代码

/**
* Definition of TreeNode:
* class TreeNode {
* public:
*     int val;
*     TreeNode *left, *right;
*     TreeNode(int val) {
*         this->val = val;
*         this->left = this->right = NULL;
*     }
* }
*/
class Solution {
/**
* @param root: The root of binary tree.
* @return: Postorder in vector which contains node values.
*/
public:
vector<int> postorderTraversal(TreeNode *root) {
// write your code here
vector<int> a;
if(root==NULL) return a;
inorder(a,root);
return a;}
void inorder(vector<int> &a,TreeNode *root)
{ if(root==NULL) return;
inorder(a,root->left);
inorder(a,root->right);
a.push_back(root->val);
}
};

后序遍历与前序遍历中序遍历除了根节点的访问顺序不同,其余都相同.