Delete node in BST

// https://leetcode.com/problems/delete-node-in-a-bst/
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left;
 *     public TreeNode right;
 *     public TreeNode(int val=0, TreeNode left=null, TreeNode right=null) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
public class Solution {
    public TreeNode DeleteNode(TreeNode root, int key)
    {
        root = SearchNode(root, key);
        return root;
    }

    TreeNode SearchNode(TreeNode node, int key)
    {
        if (node == null)
        {
            return null;
        }

        if (node.val == key)
        {
            if (node.left != null)
            {
                var maxLeft = GetMaxLeftNode(node.left);
                node.left = DeleteNode(node.left, maxLeft.val);
                maxLeft.left = node.left;
                maxLeft.right = node.right;
                return maxLeft;
            }

            if (node.right != null)
            {
                var minRight = GetMinRightNode(node.right);
                node.right = DeleteNode(node.right, minRight.val);
                minRight.left = node.left;
                minRight.right = node.right;
                return minRight;
            }

            //delete leaf node;
            return null;
        }

        if (key < node.val)
        {
            node.left = SearchNode(node.left, key);
        }
        else
        {
            node.right = SearchNode(node.right, key);
        }

        return node;
    }

    TreeNode GetMaxLeftNode(TreeNode node)
    {
        if (node == null)
        {
            return null;
        }

        TreeNode it = node;
        while(it.right != null)
        {
            it = it.right;
        }

        return it;
    }

    TreeNode GetMinRightNode(TreeNode node)
    {
        if (node == null)
        {
            return null;
        }

        TreeNode it = node;
        while(it.left != null)
        {
            it = it.left;
        }

        return it;
    }
}