leetgo/twosumiv/twosumiv.go

package twosumiv

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

func lookup(node *TreeNode, target int) bool {
	if node == nil {
		return false
	}

	if node.Val == target {
		return true
	}

	if target < node.Val {
		return lookup(node.Left, target)
	}

	return lookup(node.Right, target)
}

func recur(node *TreeNode, root *TreeNode, k int) bool {
	if node == nil {
		return false
	}
	remaining := k - node.Val

	return (remaining != node.Val && lookup(root, remaining)) ||
		recur(node.Left, root, k) ||
		recur(node.Right, root, k)
}

func findTarget(root *TreeNode, k int) bool {
	return recur(root, root, k)
}

func FindTarget(root *TreeNode, k int) bool {
	return findTarget(root, k)
}