public static void AddNextNoExtraWorker(BTree pre, BTree node)
{
if (node == null) return;
if (pre != null) pre.Next = node;
if (pre != null)
{
AddNextNoExtraWorker(pre.Right, node.Left);
}
else
{
AddNextNoExtraWorker(null, node.Left);
}
AddNextNoExtraWorker(node.Left, node.Right);
}
//add next 1, using level or BFS traverse
public static void AddNext(BTree root)
{
Queue<Tuple<BTree, int>> queue = new Queue<Tuple<BTree, int>>();
queue.Enqueue(new Tuple<BTree, int>(root, 0));
while (queue.Count > 0)
{
var node = queue.Dequeue();
if (node.Item1.Left != null)
{
queue.Enqueue(new Tuple<BTree,int>(node.Item1.Left, node.Item2 +1));
}
if (node.Item1.Right != null)
{
queue.Enqueue(new Tuple<BTree, int>(node.Item1.Right, node.Item2 + 1));
}
if (node.Item2 == queue.Peek().Item2)
node.Item1.Next = queue.Peek().Item1;
}
}
// Tree = Node ( Tree, Tree) | Node
public static BTree DeserializeTree(string format)
{
if (string.IsNullOrEmpty(format))
{
return null;
}
int index = format.IndexOf('(');
int middle = 0;
string value;
if (index > 0)
{
value = format.Substring(0, index);
middle = FindMiddleIndex(format.Substring(index + 1, format.Length - index - 2));
}
else
{
value = format.Trim();
}
BTree node = new BTree();
int v;
if (int.TryParse(value, out v))
{
node.Value = v;
}
if (middle == 0)
return node;
BTree lnode = DeserializeTree(format.Substring(index + 1, middle - index - 1));
BTree rnode = DeserializeTree(format.Substring(middle + 1, format.Length - 2 - middle));
node.Left = lnode;
node.Right = rnode;
return node;
}
public static void AddNextNoExtra(BTree root)
{
AddNextNoExtraWorker(null, root);
}
public static string SerializeTree(BTree root)
{
if (root == null)
{
return string.Empty;
}
return root.Value + "(" + SerializeTree(root.Left) + "," + SerializeTree(root.Right);
}
static int TraverseT(BTree node, List<BTree> currentTree, Dictionary<BTree, int> visitedNodes)
{
if (node == null)
{
return 0;
}
if (visitedNodes.ContainsKey(node))
{
return visitedNodes[node];
}
currentTree.Add(node);
var number = TraverseT(node.Left, currentTree, visitedNodes) + TraverseT(node.Right, currentTree, visitedNodes);
visitedNodes.Add(node, number + 1);
return number + 1;
}
public static void PreTraverse(BTree root)
{
if(root == null) return;
Console.WriteLine("visiting node {0}", root.Value);
PreTraverse(root.Left);
PreTraverse(root.Right);
}
//array of tree nodes, determine whether it forms a b-tree
//assumption1, there is no loop, it's tree node,not a graph
public static bool IsTree(BTree[] nodes)
{
//node : number of node in the tree
var visitedNodes = new Dictionary<BTree,int>();
foreach (var v in nodes)
{
if(!visitedNodes.ContainsKey(v))
{
var number = TraverseT(v, new List<BTree>(), visitedNodes);
visitedNodes[v] = number;
}
}
return nodes.Any(v => visitedNodes[v] == nodes.Length);
}
public static bool IsBalanced(BTree root, out int depth)
{
if (root == null)
{
depth = 0;
return true;
}
int ld;
var l = IsBalanced(root.Left, out ld);
int rd;
var r = IsBalanced(root.Right, out rd);
int diff = 0;
if (ld < rd) { diff = rd - ld; depth = rd; }
else{ diff = ld -rd;depth = ld;}
return diff <= 1;
}
public static void Insert(ref BTree root, int value)
{
if (root == null)
{
root = new BTree() { Value = value };
return;
}
if (value < root.Value)
{
Insert(ref root.Left, value);
}
else if (value > root.Value)
{
Insert(ref root.Right, value);
}
else
{
Console.WriteLine("duplicated value {0} skipped", value);
}
}
//if only p in tree return p
//if only q in tree return q
//if neither in tree return null
//if both in tree, return the common ancester
public static BTree FindCommonAncester(BTree root, BTree node1, BTree node2)
{
if (root == null) return null;
if (root == node1 || root == node2) return root;
var leftAncestor = FindCommonAncester(root.Left, node1, node2);
var rightAncester = FindCommonAncester(root.Right, node1, node2);
return null;
}