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LeetCode-109-Convert Sorted List to Binary Search Tree

时间:2019-02-03 11:05:02      阅读:142      评论:0      收藏:0      [点我收藏+]

标签:理解   turn   OWIN   head   ptr   bsp   more   next   height   

算法描述:

Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST.

For this problem, a height-balanced binary tree is defined as a binary tree in which the depth of the two subtrees of every node never differ by more than 1.

Example:

Given the sorted linked list: [-10,-3,0,5,9],

One possible answer is: [0,-3,9,-10,null,5], which represents the following height balanced BST:

      0
     /    -3   9
   /   /
 -10  5

解题思路:理解原理

    TreeNode* sortedListToBST(ListNode* head) {
        if(head == nullptr) return nullptr;
        return helper(head,nullptr);       
    }
    
    TreeNode* helper(ListNode* start, ListNode* end){
         if(start==end) return nullptr;
        ListNode* fast = start;
        ListNode* slow = start;
        while(fast->next!=end && fast->next->next!=end){
            fast = fast->next->next;
            slow = slow->next;
        }
        
        TreeNode* node = new TreeNode(slow->val);
        node->left = helper(start,slow);
        node->right = helper(slow->next,end);
        return node;
    }

 

LeetCode-109-Convert Sorted List to Binary Search Tree

标签:理解   turn   OWIN   head   ptr   bsp   more   next   height   

原文地址:https://www.cnblogs.com/nobodywang/p/10349596.html

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