标签：c++   leetcode   tree   recursion   

欢迎大家阅读参考，如有错误或疑问请留言纠正，谢谢

114 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;
 *     TreeNode(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); //root指针指向left，即next
        }
        if(right)
        {
            root->right = right;
            root = flattenUtil(right); //root指针指向right，即next
        }
        return root;
    }
    
    void flatten(TreeNode *root) {
        flattenUtil(root);
    }
};

leetcode_114_Flatten Binary Tree to Linked List

标签：c++   leetcode   tree   recursion   

原文地址：http://blog.csdn.net/keyyuanxin/article/details/44216837