LeetCode--Binary Tree Inorder Traversal

题目：

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]

.
代码：

/**
* Definition for a binary tree node.
* struct TreeNode {
*     int val;
*     TreeNode *left;
*     TreeNode *right;
*     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
* };
*/

vector<int> inorderTraversal(TreeNode* root) {
vector<int> vec;
stack<TreeNode*> stk;
while(root != NULL || !stk.empty())
{
while(root)  //获取最左节点，并将沿路节点入栈
{
stk.push(root);
root = root->left;
}
root = stk.top();
vec.push_back(root->val);
stk.pop();
root = root->right;
}
return vec;
}