Level order traversal using queue in swift
Swift program for Level order traversal using queue. Here problem description and explanation.
import Foundation
/*
Swift 4 program for
Level order tree traversal using queue
*/
// Create Q node
class QNode
{
var data: TreeNode? ;
var next: QNode? ;
init(_ node: TreeNode? )
{
self.data = node;
self.next = nil;
}
}
// Binary Tree Node
class TreeNode
{
var data: Int;
var left: TreeNode? ;
var right: TreeNode? ;
init(_ data: Int)
{
// Set node value
self.data = data;
self.left = nil;
self.right = nil;
}
}
class MyQueue
{
var head: QNode? ;
var tail: QNode? ;
var count: Int;
init()
{
self.head = nil;
self.tail = nil;
self.count = 0;
}
func size() -> Int
{
return self.count;
}
func isEmpty() -> Bool
{
return self.count == 0;
}
// Add new node of queue
func enqueue(_ value: TreeNode? )
{
// Create a new node
let node: QNode? = QNode(value);
if (self.head == nil)
{
// Add first element into queue
self.head = node;
}
else
{
// Add node at the end using tail
self.tail!.next = node;
}
self.count += 1;
self.tail = node;
}
// Delete a element into queue
func dequeue()
{
if (self.head == nil)
{
// Empty Queue
return;
}
// Visit next node
self.head = self.head!.next;
self.count -= 1;
if (self.head == nil)
{
// When deleting a last node of linked list
self.tail = nil;
}
}
// Get front node
func peek() -> TreeNode?
{
if (self.head == nil)
{
return nil;
}
return self.head!.data;
}
}
class BinaryTree
{
var root: TreeNode? ;
init()
{
self.root = nil;
}
func levelOrder()
{
if (self.root != nil)
{
let q: MyQueue? = MyQueue();
// Add first node
q!.enqueue(self.root);
var node: TreeNode? = self.root;
while (q!.isEmpty() == false && node != nil)
{
if (node!.left != nil)
{
// Add left child node
q!.enqueue(node!.left);
}
if (node!.right != nil)
{
// Add right child node
q!.enqueue(node!.right);
}
// Display level node
print(node!.data, terminator: " ");
// Remove current node
q!.dequeue();
// Get new head
node = q!.peek();
}
}
else
{
print("Empty Tree");
}
}
static func main(_ args: [String])
{
// Create new tree
let tree: BinaryTree? = BinaryTree();
/*
Make A Binary Tree
-----------------------
1
/ \
2 3
/ / \
4 5 6
/ / \
7 8 9
*/
// Adding tree nodes
tree!.root = TreeNode(1);
tree!.root!.left = TreeNode(2);
tree!.root!.right = TreeNode(3);
tree!.root!.right!.right = TreeNode(6);
tree!.root!.right!.left = TreeNode(5);
tree!.root!.left!.left = TreeNode(4);
tree!.root!.left!.left!.left = TreeNode(7);
tree!.root!.right!.left!.left = TreeNode(8);
tree!.root!.right!.left!.right = TreeNode(9);
// Display level order element
tree!.levelOrder();
}
}
BinaryTree.main([String]());
Output
1 2 3 4 5 6 7 8 9
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