gistfile1.txt

/**
 * Definition for a binary tree node.
 * 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 && root.Val <= high {
		return &TreeNode{
			Val : root.Val,
			Left: trimBST(root.Left,low,high),
			Right: trimBST(root.Right,low,high),
		}
	}

	a := trimBST(root.Left,low,high)
	if a != nil {
		return a
	}

	return trimBST(root.Right,low,high)
}