leetcode94 Binary Tree Inorder Traversal

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

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

return [1,3,2].

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

 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> ans;
14         if(!root)
15             return ans;
16         stack<TreeNode*> st;
17         TreeNode *rt=root;//现在要考虑的节点
18         while(rt||!st.empty())
19         {
20             while(rt)
21             {
22                 st.push(rt);
23                 rt=rt->left;
24             }
25             TreeNode *temp=st.top();
26             st.pop();
27             ans.push_back(temp->val);
28             rt=temp->right;
29         }
30         return ans;
31     }
32 };

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