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[LeetCode]Binary Tree Inorder Traversal

时间:2015-11-22 17:23:11      阅读:144      评论:0      收藏:0      [点我收藏+]

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题目描述:(链接)

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

For example:
Given binary tree {1,#,2,3},

   1
         2
    /
   3

 

return [1,3,2].

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

解题思路:

迭代版:

 1 /**
 2  * Definition for a binary tree node.
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     vector<int> inorderTraversal(TreeNode* root) {
13         vector<int> result;
14         stack<TreeNode *> cache;
15         TreeNode *p = root;
16         
17         while (!cache.empty() || p != nullptr) {
18             if (p != nullptr) {
19                 cache.push(p);
20                 p = p->left;
21             } else {
22                 p = cache.top();
23                 cache.pop();
24                 result.push_back(p->val);
25                 p = p->right;
26             }
27         }
28         
29         return result;
30     }
31 };

 递归版:

 1 /**
 2  * Definition for a binary tree node.
 3  * struct TreeNode {
 4  *     int val;
 5  *     TreeNode *left;
 6  *     TreeNode *right;
 7  *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 8  * };
 9  */
10 class Solution {
11 public:
12     vector<int> inorderTraversal(TreeNode* root) {
13         if (root != nullptr) {
14             inorderTraversal(root->left);
15             result.push_back(root->val);
16             inorderTraversal(root->right);
17         }
18         
19         return result;
20     }
21 private:
22     vector<int> result;
23 };

 

[LeetCode]Binary Tree Inorder Traversal

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原文地址:http://www.cnblogs.com/skycore/p/4986158.html

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