LeetCode Binary Tree PostorderTranversal

Problem Description

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

For example:
Given binary tree {1,#,2,3},
   1\2/3
return [3,2,1].

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

Problem Solution

1. 递归方案

/*** Definition for binary tree* struct TreeNode {*     int val;*     TreeNode *left;*     TreeNode *right;*     TreeNode(int x) : val(x), left(NULL), right(NULL) {}* };*/
class Solution {
private:vector<int> nodeVec;
public:void traverse(TreeNode *root){if(root==NULL)return;traverse(root->left);traverse(root->right);nodeVec.push_back(root->val);}vector<int> postorderTraversal(TreeNode *root) {traverse(root);return nodeVec;}
};

2. 非递归方案

/*** Definition for binary tree* struct TreeNode {*     int val;*     TreeNode *left;*     TreeNode *right;*     TreeNode(int x) : val(x), left(NULL), right(NULL) {}* };*/
class Solution {
private:vector<int> nodeVec;
public:void iterTraverse(TreeNode *root){if(root==NULL)return;stack<TreeNode*> st;TreeNode *pCur,*pPrev=NULL; //pCur: current tree node, pPrev: previous visited tree node
        st.push(root);while(!st.empty()){pCur=st.top();if((pCur->left == NULL && pCur->right == NULL) || (pPrev != NULL && (pCur->left==pPrev || pCur->right==pPrev))){nodeVec.push_back(pCur->val);                pPrev=pCur;st.pop();}else{if(pCur->right != NULL)st.push(pCur->right);if(pCur->left != NULL)st.push(pCur->left);}}}vector<int> postorderTraversal(TreeNode *root) {iterTraverse(root);return nodeVec;}
};

转载于:https://www.cnblogs.com/ballwql/p/3668357.html

LeetCode Binary Tree PostorderTranversal相关推荐

[LeetCode] Binary Tree Level Order Traversal 二叉树层次遍历(DFS | BFS)
目录: 1.Binary Tree Level Order Traversal - 二叉树层次遍历 BFS 2.Binary Tree Level Order Traversal II - 二叉树层次 ...
Leetcode | Binary Tree Maximum Path Sum
Given a binary tree, find the maximum path sum. The path may start and end at any node in the tree. ...
LeetCode Binary Tree Right Side View(搜索)
问题:给出一个二叉树,要求输出右视图思路:因为要求输出右视图.可以考虑使用深度优先搜索或者广度优先搜索. 使用深度优先搜索时,以非递归形式,将左右子树入栈,同时使用哈希表记录深度与对应右视图的值. ...
LeetCode Binary Tree Preorder Traversal(二叉树的前序遍历)
问题:给出一个二叉树,输出前序遍历思路: 自顶向下遍历过程中,将当前结点的值加入到list中,然后处理左.右子树具体代码参考: https://github.com/wuli2496/OJ/tre ...
[LeetCode] Binary Tree Postorder Traversal 二叉树的后序遍历
Given a binary tree, return the postorder traversal of its nodes' values. For example: Given binary ...
[LeetCode] Binary Tree Postorder题解
Binary Tree Postorder Given a binary tree, return the postorder traversal of its nodes' values. For ...
[Leetcode] Binary Tree Maximum Path Sum
这是LeetCode上的一道题目,需要求二叉树中两点路径的最大和.原题是 https://oj.leetcode.com/problems/binary-tree-maximum-path-sum/ ...
[leetcode] Binary Tree Preorder Traversal
Given a binary tree, return the preorder traversal of its nodes' values. For example: Given binary t ...
LeetCode Binary Tree Inorder Traversal
Given a binary tree, return the inorder traversal of its nodes' values. For example: Given binary tr ...

LeetCode Binary Tree PostorderTranversal

LeetCode Binary Tree PostorderTranversal相关推荐

最新文章

热门文章