trim-a-binary-search-tree.go

package trimabinarysearchtree

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

func trimBST(root *TreeNode, low int, high int) *TreeNode {
	if root == nil {
		return nil
	}

	if root.Val < low {
		return trimBST(root.Right, low, high)
	}

	if root.Val > high {
		return trimBST(root.Left, low, high)
	}

	root.Left = trimBST(root.Left, low, high)
	root.Right = trimBST(root.Right, low, high)

	return root
}