LeetCode/108. ConvertSortedArrayToBST

Summary

I was taking break way more than it should be. Also I totally misunderstood this problem.
I really should read document carefully.

Solutions

My Solution

The below is my first solution without caring many things.

public class ConvertSortedArrayToBST
{
    public TreeNode SortedArrayToBST(int[] nums)
    {
        if (nums.Length == 0) return null;

        var output = new TreeNode(0);

        Recursion(ref output.left, nums);

        return output.left;
    }

    private void Recursion(ref TreeNode output, int[] nums)
    {
        if (nums.Length == 0) return;

        int mIdx = nums.Length / 2;
        output = new TreeNode(nums[mIdx]);

        Recursion(ref output.left, nums.Take(mIdx).ToArray());
        Recursion(ref output.right, nums.Skip(mIdx + 1).ToArray());
    }
}

Best Solution

This is a better solution that rather modifying array and passing it, sending low and high indexes.
Explicitly selecting the value by index, this will be the ideal solution and which I need to learn.

public class ConvertSortedArrayToBST
{
    public TreeNode SortedArrayToBST(int[] nums)
    {
        if (nums.Length == 0) return null;

        return BestSolution(nums, 0, nums.Length - 1);
    }

    private TreeNode BestSolution(int[] nums, int low, int high)
    {
        if (low > high) return null;

        int mid = (low + high) / 2;
        var node = new TreeNode(nums[mid]);
        node.left = BestSolution(nums, low, mid - 1);
        node.right = BestSolution(nums, mid + 1, high);
        return node;
    }
}
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