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[LeetCode]Binary Tree Inorder Traversal

时间:2015-09-04 23:57:27      阅读:365      评论:0      收藏:0      [点我收藏+]

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Binary Tree Inorder Traversal

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?

confused what "{1,#,2,3}" means? > read more on how binary tree is serialized on OJ.

 

中序遍历。左-根-右。迭代使用stack。

 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         if(!root) return result;
15         TreeNode* p;
16         stack<TreeNode*> mystack;
17         p = root;
18         while(!mystack.empty() || p)
19         {
20             if(p)
21             {
22                 mystack.push(p);
23                 p = p->left;
24             }
25             else
26             {
27                 p = mystack.top();
28                 mystack.pop();
29                 result.push_back(p->val);
30                 p = p->right;
31             }
32         }
33         return result;
34     }
35 };

递归的方法很统一。先序,中序,后续,只要修改遍历的顺序即可。

 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         traversal(root,result);
15         return result;
16     }
17     void traversal(TreeNode* root,vector<int>& ret)
18     {
19         if(root)
20         {
21             traversal(root->left,ret);
22             ret.push_back(root->val);
23             traversal(root->right,ret);
24         }
25     }
26 };

 

[LeetCode]Binary Tree Inorder Traversal

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原文地址:http://www.cnblogs.com/Sean-le/p/4782590.html

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