LeetCode_Binary Tree Inorder Traversal

/**
 * 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) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        stack<TreeNode *> myStack;
        vector<int> result;
        if(root == NULL) return  result;
        TreeNode *current;
        current = root;
        while(current ||myStack.size()>0)
        {
           while(current){
             myStack.push(current);
             current = current->left;
           }
           
            if(myStack.size()>0)
            {
               current = myStack.top();
               myStack.pop();
               result.push_back(current->val);
               current = current->right;
            }
        }
        return result;
    }
};

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惭愧，inorder traversal 非递归实现竟然搞了半天，明天把四种遍历方法都写一遍，多复习几遍