Flatten Binary Tree to Linked List @leetcode

=看完别人的代码，就无限接近于认为自己是沙茶。大家的思路怎么这么简洁，以至于我能看懂，我估计我的代码别人都看不懂。

void flatten(TreeNode *root) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        TreeNode*tmp;
        flattenpiece(root,tmp);
    }
    void flattenpiece(TreeNode *root,TreeNode *&tail){
        if(root == NULL)
            return;
        TreeNode*leftTreeRoot = root->left;
        TreeNode*rightTreeRoot = root->right;
        if(leftTreeRoot == NULL)
        {
            TreeNode*tmp;
            flattenpiece(rightTreeRoot,tmp);
            if(rightTreeRoot == NULL)
                tail = root;
            else
                tail =tmp;
            return;
        }
        //TreeNode*leftTreeTail;
        flattenpiece(leftTreeRoot,tail);
        root->right = leftTreeRoot;
        root->left = NULL;
        if(tail)
        {
            if(rightTreeRoot)
            {
                tail->right = rightTreeRoot;
                tail->left = NULL;
                tail = rightTreeRoot;
            }
        }
        flattenpiece(rightTreeRoot,tail);
    }
}

=思路嗷嗷清晰的人的代码：

/**
 * Definition for binary tree
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    void flatten(TreeNode *root) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        if (root == NULL) return;
        if (root->left == NULL && root->right == NULL) {
            return;
        } else if (root->left == NULL) {
            flatten(root->right);
        } else if (root->right == NULL) {
            root->right = root->left;
            root->left = NULL;
            flatten(root->right);
        } else {
            flatten(root->left);
            flatten(root->right);
            TreeNode* p = root->left;
            while (p->right) {
                p = p->right;
            }
            p->right = root->right;
            root->right = root->left;
            root->left = NULL;
         }
    }
};

=我是弧度