module BinaryTree

( BinaryTree (..)

, nullNode

, newNode

, getValue

, setValue

, getLeft

, getRight

, setLeft

, setRight

, getChildrenNumber

, isNullNode

) where

data BinaryTree = NULL | BinaryTree Integer BinaryTree BinaryTree deriving (Eq, Show)

-- | Create the NULL node

nullNode :: BinaryTree

nullNode = NULL

-- | Create the new node

newNode :: Integer -> BinaryTree

newNode nodeValue = BinaryTree nodeValue NULL NULL

-- | Get the value of the given node

getValue :: BinaryTree -> Integer

getValue NULL = error "Cannot get the value of the NULL node!"

getValue (BinaryTree nodeValue leftChild rightChild) = nodeValue

-- | Set the value of the given node

setValue :: BinaryTree -> Integer -> BinaryTree

setValue NULL nodeValue = BinaryTree nodeValue NULL NULL

setValue (BinaryTree nodeValue leftChild rightChild) newValue = BinaryTree newValue leftChild rightChild

-- | Get the left child of the node

getLeft :: BinaryTree -> BinaryTree

getLeft (BinaryTree nodeValue leftChild rightChild) = leftChild

-- | Get the right child of the node

getRight :: BinaryTree -> BinaryTree

getRight (BinaryTree nodeValue leftChild rightChild) = rightChild

-- | Change the value of the left child of the node

setLeft :: BinaryTree -> Integer -> BinaryTree

setLeft (BinaryTree nodeValue leftChild rightChild) newValue = BinaryTree nodeValue (setValue leftChild newValue) rightChild

-- | Change the value of the right child of the node

setRight :: BinaryTree -> Integer -> BinaryTree

setRight (BinaryTree nodeValue leftChild rightChild) newValue = BinaryTree nodeValue leftChild (setValue rightChild newValue)

-- | Get the number of the children of the given node

getChildrenNumber :: BinaryTree -> Integer

getChildrenNumber (BinaryTree nodeValue leftChild rightChild)

| leftChild == NULL && rightChild == NULL = 0

| leftChild == NULL || rightChild == NULL = 1

| otherwise = 2

-- | Check if the given node is a null node

isNullNode :: BinaryTree -> Bool

isNullNode NULL = True

isNullNode _ = False

main :: IO ()

main = do

print nullNode

let node1 = newNode 1

print node1

print (getValue node1)

let node2 = setValue node1 3

print node2

print (getValue node2)

print (getLeft node1)

print (getRight node1)

let node3 = setLeft node1 10

print node3

let node4 = setRight node3 15

print node4

putStr "\n"

print (node1 == node2)

print (node1 == node1)

putStr "\n"

print node1

print node2

print node3

print node4

putStr "\n"

print (getChildrenNumber node1)

print (getChildrenNumber node2)

print (getChildrenNumber node3)

print (getChildrenNumber node4)

putStr "\n"

print (isNullNode nullNode)

print (isNullNode node1)

print (isNullNode node3)