Leetcode-108. Convert an ordered array to a binary search tree

topic:

https://leetcode-cn.com/problems/convert-sorted-array-to-binary-search-tree/

answer:

Recursive divide and conquer:

  public TreeNode sortedArrayToBST(int[] nums) {

         return createBST(nums,0,nums.length-1);

    }

 

     public TreeNode createBST(int[] nums, int l,int r){

        if(l>r) return null;

        int mid = l + (r-l)/2;

        TreeNode treeNode = new TreeNode(nums[mid]);

        treeNode.left = createBST(nums,l,mid-1);

        treeNode.right = createBST(nums,mid+1,r);

        return treeNode;

    }