private static TreeNode CreateTree(Node current)
{
if (current == null)
{
return null;
}
var root = new TreeNode { value = current.value };
var currentT = root;
current = current.next;
int i = 1;
var treeQueue = new Queue<TreeNode>();
while (current != null)
{
var treeNode = new TreeNode { value = current.value };
current = current.next;
if (i == 1)
{
currentT.left = treeNode;
treeQueue.Enqueue(currentT.left);
i++;
}
else if (i == 2)
{
currentT.right = treeNode;
treeQueue.Enqueue(currentT.right);
i++;
}
if(i >= 3)
{
i = 1;
currentT = treeQueue.Dequeue();
}
}
return root;
}
private static TreeNode CreateTreeFromInorderPreorder(List<int> inorderList, List<int> preorderList, ref int preorderIndex)
{
if (!inorderList.Any() || !preorderList.Any() || preorderIndex >= preorderList.Count)
{
return null;
}
preorderIndex = preorderIndex + 1;
var root = new TreeNode { value = preorderList[preorderIndex] };
var rootIndex = inorderList.IndexOf(preorderList[preorderIndex]);
var inorderLeft = inorderList.Where((value, index) => index < rootIndex).ToList();
var inorderRight = inorderList.Where((value, index) => index > rootIndex).ToList();
//var preorderLeft = preorderList.Where(inorderLeft.Contains).ToList();
//var preorderRight = preorderList.Where(inorderRight.Contains).ToList();
root.left = CreateTreeFromInorderPreorder(inorderLeft, preorderList, ref preorderIndex);
root.right = CreateTreeFromInorderPreorder(inorderRight, preorderList, ref preorderIndex);
return root;
}
private static void PrintTreePreOrder(TreeNode head)
{
if (head == null)
{
return;
}
Console.Write(head.value + " ");
PrintTreePreOrder(head.left);
PrintTreePreOrder(head.right);
}
private static void PrintTreeLevelByLevel(TreeNode head)
{
var nodeQueue = new Queue<TreeNode>();
nodeQueue.Enqueue(head);
while (nodeQueue.Count > 0)
{
var tempQueue = new Queue<TreeNode>();
while (nodeQueue.Count > 0)
{
var node = nodeQueue.Dequeue();
if (node != null)
{
Console.Write(node.value + " ");
tempQueue.Enqueue(node.left);
tempQueue.Enqueue(node.right);
}
}
Console.WriteLine();
nodeQueue = tempQueue;
}
}
private static void PrintTree(TreeNode root)
{
Console.WriteLine("Preorder ");
PrintTreePreOrder(root);
Console.WriteLine();
Console.WriteLine("Inorder ");
PrintTreeInOrder(root);
Console.WriteLine();
Console.WriteLine("PostOrder ");
PrintTreePostOrder(root);
Console.WriteLine();
Console.WriteLine("Print level by level ");
PrintTreeLevelByLevel(root);
Console.WriteLine();
}
private static bool IsBST(TreeNode node)
{
if (node != null)
{
var left = node.left != null ? node.left.value : int.MinValue;
var right = node.right != null ? node.right.value : int.MaxValue;
if (left > node.value || node.value > right)
{
return false;
}
return IsBST(node.left) && IsBST(node.right);
}
return true;
}
private static void InsertBST(ref TreeNode root, int value)
{
if (root == null)
{
root = new TreeNode { value = value };
return;
}
if (root.value <= value)
{
InsertBST(ref root.right, value);
}
else
{
InsertBST(ref root.left, value);
}
}
private static TreeNode GetLowestCommonAncestor(TreeNode root, int input1, int input2)
{
if (root == null)
{
return null;
}
if (root.value >= input1 && root.value <= input2)
{
return root;
}
if (root.value < input1 && root.value < input2)
{
return GetLowestCommonAncestor(root.right, input1, input2);
}
return GetLowestCommonAncestor(root.left, input1, input2);
}
