题解 | 将升序数组转化为平衡二叉搜索树

/**
 * struct TreeNode {
 *	int val;
 *	struct TreeNode *left;
 *	struct TreeNode *right;
 *	TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 * };
 */
class Solution {
public:
    TreeNode* buildTree(vector<int>& nums, int l, int r) {
        if (l > r) return nullptr;

        int mid = (r - l) / 2 + l;
        TreeNode* root = new TreeNode(nums[mid]);
        root->left = buildTree(nums, l, mid - 1);
        root->right = buildTree(nums, mid + 1, r);

        return root;
    }

    TreeNode* sortedArrayToBST(vector<int>& nums) {
        TreeNode *root = buildTree(nums, 0, nums.size() - 1);
        return root;
    }
};