108. Convert Sorted Array to Binary Search Tree

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problem

solution

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class Solution {
public:
    TreeNode* sortedArrayToBST(vector<int>& nums) {
        if(nums.empty()) return nullptr;
        int n = nums.size();
        TreeNode *root = new TreeNode(nums[n/2]);
        vector<int> left(nums.begin(), nums.begin()+n/2);
        vector<int> right(nums.begin()+n/2+1, nums.end());
        root->right = sortedArrayToBST(right);
        root->left = sortedArrayToBST(left);
        return root;
    }
};

analysis

  • time complexity O(n)
  • space complexity O(n)