108 - 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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本文介绍了一种将有序数组转换为高度平衡二叉搜索树(BST)的方法。通过递归方式，选择数组中间元素作为根节点，再递归地创建左右子树。此方法确保了树的高度平衡。

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

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思路分析：

递归。

class Solution {
public:
    TreeNode *createTree(vector<int> &num, int left, int right)
    {
        if (left > right)
            return NULL;
            
        int mid = (left + right) / 2;
        
        TreeNode *leftNode = createTree(num, left, mid - 1);
        TreeNode *rightNode = createTree(num, mid + 1, right);
        
        TreeNode *node = new TreeNode(num[mid]);
        
        node->left = leftNode;
        node->right = rightNode;
        
        return node;
    }
    
    TreeNode *sortedArrayToBST(vector<int> &num) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
        return createTree(num, 0, num.size() - 1);    
    }
};