94. Binary Tree Inorder Traversal

• 中序遍历二叉树(非递归)
  使用一个辅助栈
  题目来源

• C++实现

/**
 * Definition for a binary tree node.
 * 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)
    {
        stack<TreeNode*> data;
		vector<int> treedata;
		
		while(!data.empty() || root != NULL)
		{
			if(root != NULL)
			{
				data.push(root);
				root = root->left;
			}
			else
			{
				root = data.top();
                treedata.push_back(root->val);
				data.pop();
				root = root->right;
			}
		}
		
		return treedata;
    }
};