94 Binary Tree Inorder Traversal(二叉树中序遍历Medium)

 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             stack<TreeNode*> s;
16             TreeNode* temp=root;
17             while(temp!=NULL||!s.empty()){
18                 while(temp!=NULL){
19                     s.push(temp);                //将所有的左节点入栈
20                     temp=temp->left;
21                 }
22                 temp=s.top();                      
23                 s.pop();
24                 ans.push_back(temp->val);        //添加最下面的左节点
25                 temp=temp->right;                //添加倒数第二个左节点的右节点    
26             }
27         }
28         return ans;
29     }
30 };