Leetcode_114_flatten Binary Tree to Linked List

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Flatten Binary Tree to Linked List

Given a binary tree, flatten it to a linked list in-place.

For example,
Given

1
/ \
2 5
/ \   \
3 4 6
The flattened tree should look like:
1
\
2
\
3
\
4
\
5
\
6

/** * Definition for binary tree * struct TreeNode {*     int val; *     TreeNode *left; *     TreeNode *right; *     Tre Enode (int x): Val (x), left (null), right (NULL) {} *}; */class Solution {public:    treenode* flattenutil (TreeNode *root)    {        if (root==null  )            return NULL;        TreeNode *left = root->left;        TreeNode *right = root->right;                Root->left = NULL;        if (left)        {            root->right = left;            Root = Flattenutil (left); The root pointer points to left, that is, next        }        if (right)        {            root->right = right;            root = Flattenutil (right); The root pointer points to right, next        }        return root    ;        void Flatten (TreeNode *root) {        flattenutil (root);    }};

Leetcode_114_flatten Binary Tree to Linked List