private int GetTree(ChallengeTreeNode parent, string data, int index)
{
//this function should always be called on an opening backet
index = AdvanceString(index, "(");
var nextSymbol = GetNextSymbol(data, index);
if (nextSymbol != ",")
{
parent.left = new ChallengeTreeNode(int.Parse(nextSymbol));
index = AdvanceString(index, nextSymbol);
if (GetNextSymbol(data, index) == "(")
{
index = GetTree(parent.left, data, index);
}
}
//here, we should find a comma
index = AdvanceString(index, ",");
nextSymbol = GetNextSymbol(data, index);
if (nextSymbol != ")")
{
parent.right = new ChallengeTreeNode(int.Parse(nextSymbol));
index = AdvanceString(index, nextSymbol);
if (GetNextSymbol(data, index) == "(")
{
index = GetTree(parent.right, data, index);
}
}
//here, we should find a right bracket
index = AdvanceString(index, ")");
//last thing, return our data string
return(index);
}
public static ChallengeTreeNode MakeTreeFromString(string s)
{
var entries = s.Split(',').Select(r => r.Trim()).ToList();
Queue <ChallengeTreeNode> nodes = new Queue <ChallengeTreeNode>();
var root = new ChallengeTreeNode(int.Parse(entries[0]));
nodes.Enqueue(root);
for (var i = 1; i < entries.Count; i += 2)
{
var node = nodes.Dequeue();
var valLeft = entries[i];
var valRight = entries[i + 1];
if (valLeft != "null")
{
var leftNode = new ChallengeTreeNode(int.Parse(valLeft));
node.left = leftNode;
nodes.Enqueue(leftNode);
}
if (valRight != "null")
{
var rightNode = new ChallengeTreeNode(int.Parse(valRight));
node.right = rightNode;
nodes.Enqueue(rightNode);
}
}
return(root);
}
// Encodes a tree to a single string.
public string serialize(ChallengeTreeNode root)
{
if (root == null)
{
return("");
}
var builder = new StringBuilder();
GetString(root, builder);
return(builder.ToString());
}
private void GetString(ChallengeTreeNode node, StringBuilder builder)
{
builder.Append(node.val);
if (node.left == null && node.right == null)
{
return;
}
builder.Append('(');
if (node.left != null)
{
GetString(node.left, builder);
}
builder.Append(',');
if (node.right != null)
{
GetString(node.right, builder);
}
builder.Append(')');
}
// Decodes your encoded data to tree.
public ChallengeTreeNode deserialize(string data)
{
if (string.IsNullOrEmpty(data))
{
return(null);
}
var rootVal = GetNextSymbol(data, 0);
var root = new ChallengeTreeNode(int.Parse(rootVal));
var index = AdvanceString(0, rootVal);
if (index == data.Length)
{
return(root);
}
GetTree(root, data, index);
return(root);
}
private ChallengeTreeNode ConstructNode(Stack <int> preorderStack, List <int> inorderList)
{
var nodeVal = preorderStack.Pop();
var valInorderIndex = inorderList.IndexOf(nodeVal);
var inorderLeft = inorderList.GetRange(0, valInorderIndex);
var inorderRight = inorderList.GetRange(valInorderIndex + 1, inorderList.Count - valInorderIndex - 1);
var node = new ChallengeTreeNode(nodeVal);
if (inorderLeft.Count != 0)
{
node.left = ConstructNode(preorderStack, inorderLeft);
}
if (inorderRight.Count != 0)
{
node.right = ConstructNode(preorderStack, inorderRight);
}
return(node);
}
public NodeAndVal(ChallengeTreeNode root, int val)
{
Root = root;
Val = val;
}
