Golang Leetcode 669. Trim a Binary Search Tree.go

type TreeNode struct {
	Val   int
	Left  *TreeNode
	Right *TreeNode
}

func trimBST(root *TreeNode, L int, R int) *TreeNode {

	if root == nil {
		return root
	}
	if root.Val > R {
		return trimBST(root.Left, L, R)
	}
	if root.Val < L {
		return trimBST(root.Right, L, R)
	}
	root.Left = trimBST(root.Left, L, R)
	root.Right = trimBST(root.Right, L, R)
	return root
}