LeetCode Convert Sorted Array to Binary Search Tree

最新推荐文章于 2020-08-07 10:05:40 发布

原创最新推荐文章于 2020-08-07 10:05:40 发布 · 266 阅读

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本文介绍了一种将已排序的数组转换为高度平衡的二叉搜索树的方法。通过递归地选取中间元素作为根节点，并左右分割数组来构建左右子树，确保了树的高度平衡。

题目：

Given an array where elements are sorted in ascending order, convert it to a height balanced BST.

/**
 * 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 *sortedArrayToBST(vector<int> &num) {
    	TreeNode *root = create(num, 0, num.size()-1);
    	return root; 	
    }
private:
	TreeNode *create(vector<int> &num, int begin, int end) {
		if(begin <= end) {
			int mid = begin + (end-begin)/2;
			TreeNode *root = new TreeNode(num[mid]);
			root->left = create(num, begin, mid-1);
			root->right = create(num, mid+1, end);	
			return root;
		}
		else
		 	return NULL;
	}
};