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This is a test article.

Growth Mindset

Always do the right thing and wait for time.
Embrace challenges, see failures as essential to mastery, difficulties as opportunity to progress.
What exactly is your problem?
Have you ever met this kind of problems?
What is your solution? How do you solve your problem, in every possible way, in your best way?
Look back and ask yourself what could you have done? How will you do for the next time you meet similar problems?

Binary Tree Inorder Traversal

leetcode: 22. Binary Tree Inorder Traversal

/**
 * 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) {
        vector<int> res;
        if (!root) return res;
        TreeNode *cur, *pre;
        cur = root;
        while (cur) {
            if (!cur->left) {
                res.push_back(cur->val);
                cur = cur->right;
            } else {
                pre = cur->left;
                while (pre->right && pre->right != cur) pre = pre->right;
                if (!pre->right) {
                    pre->right = cur;
                    cur = cur->left;
                } else {
                    pre->right = NULL;
                    res.push_back(cur->val);
                    cur = cur->right;
                }
            }
        }
        return res;
    }
};