[Golang][Leetcode][BinaryTree]刷題系列-108-Convert Sorted Array to Binary Search Tree

Contents
108. Convert Sorted Array to Binary Search Tree
Level : Easy
原題連結 : Click
題目 :
Given an integer array nums where the elements are sorted in ascending order, convert it to a height-balanced binary search tree.
A height-balanced binary tree is a binary tree in which the depth of the two subtrees of every node never differs by more than one.
Example :
Note
Example 1:
Input: nums = [-10,-3,0,5,9] Output: [0,-3,9,-10,null,5] Explanation: [0,-10,5,null,-3,null,9] is also accepted:
Example 2:
Input: nums = [1,3] Output: [3,1] Explanation: [1,3] and [3,1] are both a height-balanced BSTs.
解題思路 :
- 這題需要我們將遞增序列的數列轉換成height-balacend的BST,題目定義為每一個node所連接的左右subtree之間深度不能差超過1
- 其實呢這題考察我們對BST的熟悉度跟Recursive的熟練度
- 若要左右高度相仿的subtree,那該root必須是該遞增序列的中位數才能使得左右subtree node數平均分布,然後每一個node都遵守與root一樣的準則寫出recursive code
Recursive解法
- time complexity: O(n) , space complexity: O(1)
Runtime: 0 ms, faster than 100.00% of Go online submissions for Convert Sorted Array to Binary Search Tree.
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