Convert Sorted Array to Binary Search Tree

最新推荐文章于 2022-02-19 22:56:38 发布

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本文介绍了一种方法，通过给定的升序排序数组构建一个高度平衡的二叉搜索树（BST）。详细阐述了如何利用中点分割数组并递归构建左子树和右子树的过程。

Convert Sorted Array to Binary Search Tree

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 *buildTree(vector<int> &num, int begin, int end)
    {
        if(begin >= end)
        {
            return NULL;
        }
        int mid = (begin + end - 1)/2;
        TreeNode* p = new TreeNode(num[mid]);
        TreeNode* lc = buildTree(num, begin, mid);
        TreeNode* lr = buildTree(num, mid+1, end);
        p->right = lr;
        p->left = lc;
        return p;
    }
    TreeNode *sortedArrayToBST(vector<int> &num) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        return buildTree(num, 0, num.size());
    }
};