leetcode[94]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.

/**
* Definition for binary tree
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/
class Solution {
public:
vector<int> inorderTraversal(TreeNode *root)
{
vector<int> res;
if(root==NULL)return res;
TreeNode *p=root;
stack<TreeNode *> sta;
while(p!=NULL||!sta.empty())
{
while(p!=NULL)
{
sta.push(p);
p=p->left;
}
if(!sta.empty())
{
p=sta.top();
sta.pop();
res.push_back(p->val);
p=p->right;
}
}
return res;
}
/*
void inorder(TreeNode *root, vector<int> &res)
{
if(root==NULL)return;
inorder(root->left,res);
res.push_back(root->val);
inorder(root->right,res);
return;
}
vector<int> inorderTraversal(TreeNode *root) {
vector<int> res;
inorder(root,res);
return res;
}
*/
};