给出一棵二叉树,返回其节点值的后序遍历。
样例
给出一棵二叉树 {1,#,2,3}
,
1 2 / 3
返回 [3,2,1]
分析:后序遍历要比先序,中序要难一些。 后序是左右根。
/** * 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 TreeNode *curr,*pre; vector<int> res; stack<TreeNode *>s; curr=root; do { while(curr!=NULL) { s.push(curr); curr=curr->left; } pre=NULL; while(!s.empty()) { curr=s.top(); s.pop(); if(curr->right==pre) { res.push_back(curr->val); pre=curr; } else { s.push(curr); curr=curr->right; break; } } }while(!s.empty()); return res; } };
时间: 2024-11-06 03:38:40