public static int[] InorderIterative(Node root)
{
var s = new Stack<Node>();
var curr = root;
s.Push(curr);
while (curr.Left != null)
{
s.Push(curr.Left);
curr = curr.Left;
}
int i = 0;
var order = new int[root.Size + 1];
while (s.Count != 0)
{
var node = s.Pop();
order[i++] = node.Key;
if (node.Right != null)
{
var localNode = node.Right;
s.Push(localNode);
while (localNode.Left != null)
{
s.Push(localNode.Left);
localNode = localNode.Left;
}
}
}
return order;
}
public static uint FindHeightIter(Node root)
{
if (root == null) { return 0; }
var q = new Queue<Node>();
q.Enqueue(root);
q.Enqueue(null);
uint height = 0;
while (q.Count > 1)
{
root = q.Dequeue();
if (root == null)
{
height++;
q.Enqueue(null);
continue;
}
if (root.Left != null)
{
q.Enqueue(root.Left);
}
if (root.Right != null)
{
q.Enqueue(root.Left);
}
}
return height + 1;
}
public static uint FindMaxDiameter(Node root)
{
if (root == null) return 0;
var lheight = FindHeight(root.Left);
var rheight = FindHeight(root.Right);
var ldiameter = FindMaxDiameter(root.Left);
var rdiameter = FindMaxDiameter(root.Right);
return Math.Max(lheight + rheight + 1, Math.Max(ldiameter, rdiameter));
}
public static int[] Inorder(Node root)
{
var order = new List<int>(root.Size + 1);
InorderTraversal(root, order);
return order.ToArray();
}
private static void PreOrderRecursive(Node root, List<int> order)
{
if (root == null) { return; }
order.Add(root.Key);
PreOrderRecursive(root.Left, order);
PreOrderRecursive(root.Right, order);
}
private static void InorderTraversal(Node root, List<int> order)
{
if (root == null)
{ return; }
InorderTraversal(root.Left, order);
order.Add(root.Key);
InorderTraversal(root.Right, order);
}
private static bool AreSameTrees(Node a, Node b)
{
if (a == null && b == null) { return true; }
if ((a == null && b != null) || (a != null && b == null))
{
return false;
}
if (a.Key == b.Key)
{
return AreSameTrees(a.Left, b.Left) && AreSameTrees(a.Right, b.Right);
}
return false;
}
public static Node InvertTreeRecurse(Node root)
{
if (root == null) { return null; }
var right = InvertTreeRecurse(root.Right);
var left = InvertTreeRecurse(root.Left);
root.Left = right;
root.Right = left;
return root;
}
public static int[] ZigzagOrder(Node root)
{
if (root == null) { return new int[0]; }
var order = new int[root.Size + 1];
var s1 = new Stack<Node>();
var s2 = new Stack<Node>();
s1.Push(root);
int i = 0;
while (s1.Count != 0 || s2.Count != 0)
{
while (s1.Count != 0)
{
root = s1.Pop();
order[i++] = root.Key;
if (root.Left != null)
{
s2.Push(root.Left);
}
if (root.Right != null)
{
s2.Push(root.Right);
}
}
while (s2.Count != 0)
{
root = s2.Pop();
order[i++] = root.Key;
if (root.Right != null)
{
s1.Push(root.Right);
}
if (root.Left != null)
{
s1.Push(root.Left);
}
}
}
return order;
}
public static int[] PreOrderIterative(Node root)
{
var order = new int[root.Size + 1];
int i = 0;
var q = new Stack<Node>();
q.Push(root);
while (q.Count != 0)
{
var node = q.Pop();
order[i++] = node.Key;
if (node.Right != null)
{ q.Push(node.Right); }
if (node.Left != null)
{ q.Push(node.Left); }
}
return order;
}
public static int[] PreOrder(Node root)
{
var order = new List<int>(root.Size + 1);
PreOrderRecursive(root, order);
return order.ToArray();
}
public static int[] PostOrderIterative(Node root)
{
var order = new int[root.Size + 1];
int i = 0;
var s = new Stack<Node>();
do
{
while (root != null)
{
if (root.Right != null)
{ s.Push(root.Right); }
s.Push(root);
root = root.Left;
}
root = s.Pop();
if (root.Right != null && s.Count > 0 && s.Peek() == root.Right)
{
s.Pop();
s.Push(root);
root = root.Right;
}
else
{
order[i++] = root.Key;
root = null;
}
} while (s.Count != 0);
return order;
}
public static int[] LevelOrder(Node root)
{
if (root == null) { return new int[0]; }
var order = new int[root.Size + 1];
var q = new Queue<Node>();
int i = 0;
q.Enqueue(root);
while (q.Count != 0)
{
root = q.Dequeue();
order[i++] = root.Key;
if (root.Left != null)
{
q.Enqueue(root.Left);
}
if (root.Right != null)
{
q.Enqueue(root.Right);
}
}
return order;
}
public static bool IsSubtree(Node root, Node find)
{
if (root == null || find == null) { return false; }
var q = new Queue<Node>();
q.Enqueue(root);
var found = false;
while (q.Count > 0 && !found)
{
root = q.Dequeue();
if (root.Key == find.Key)
{
found = AreSameTrees(root, find);
}
if (root.Left != null)
{
q.Enqueue(root.Left);
}
if (root.Right != null)
{
q.Enqueue(root.Right);
}
}
return found;
}
public static uint FindHeight(Node root)
{
if (root == null) { return 0; }
return Math.Max(FindHeight(root.Left), FindHeight(root.Right)) + 1;
}
public Node(int key, Node parent)
{
this.Parent = parent;
this.Size = 0;
this.Key = key;
}
public static Node InvertTree(Node root)
{
if (root == null) { throw new ArgumentNullException(); }
var q = new Queue<Node>();
q.Enqueue(root);
Node node;
while (q.Count > 0)
{
node = q.Dequeue();
//queue if exists
if (node.Left != null)
{
q.Enqueue(node.Left);
}
if (node.Right != null)
{
q.Enqueue(node.Right);
}
//swap
var temp = node.Right;
if (node.Right != null) { node.Right = node.Left; }
if (temp != null) { node.Left = temp; }
}
return root;
}