public static string InOrderTraversalReturnAsString(BinaryTreeNode <int> treeNode)
{
StringBuilder returnString = new StringBuilder();
StackViaLinkedList <BinaryTreeNode <int> > st = new StackViaLinkedList <BinaryTreeNode <int> >();
st.Push(treeNode);
BinaryTreeNode <int> currentNode = treeNode;
bool shouldCheckLeft = true;
while (!st.IsEmpty())
{
while (currentNode.Left != null && shouldCheckLeft)
{
st.Push(currentNode.Left);
currentNode = currentNode.Left;
}
currentNode = st.Pop().Data;
shouldCheckLeft = false;
returnString.Append(currentNode.Data + " ");
if (currentNode.Right != null)
{
st.Push(currentNode.Right);
currentNode = currentNode.Right;
shouldCheckLeft = true;
}
}
return(returnString.ToString());
}
public void Pop_Test()
{
IStack <char> stack = new StackViaLinkedList <char>();
stack.Push('A');
stack.Push('B');
stack.Push('C');
stack.Push('D');
stack.Push('E');
stack.IsEmpty.Should().BeFalse();
stack.Count.Should().Be(5);
stack.Pop().Should().Be('E');
stack.Count.Should().Be(4);
stack.Pop().Should().Be('D');
stack.Count.Should().Be(3);
stack.Pop().Should().Be('C');
stack.Count.Should().Be(2);
stack.Pop().Should().Be('B');
stack.Count.Should().Be(1);
stack.Pop().Should().Be('A');
stack.Count.Should().Be(0);
Action act = () => stack.Pop();
act.Should().Throw <IndexOutOfRangeException>()
.WithMessage("Stack is empty.");
}
public void NonEmptyStackHasCorrectEmptyFlag()
{
var s = new StackViaLinkedList <int>();
s.Push(34);
Assert.False(s.IsEmpty());
}
public static void InOrderTraversalIterative(BinarySearchTreeNode <int> treeNode)
{
StackViaLinkedList <BinarySearchTreeNode <int> > st = new StackViaLinkedList <BinarySearchTreeNode <int> >();
st.Push(treeNode);
BinarySearchTreeNode <int> currentNode = treeNode;
bool shouldCheckLeft = true;
while (!st.IsEmpty())
{
while (currentNode.Left != null && shouldCheckLeft)
{
st.Push(currentNode.Left);
currentNode = currentNode.Left;
}
currentNode = st.Pop().Data;
shouldCheckLeft = false;
Console.Write(currentNode.Data + " ");
if (currentNode.Right != null)
{
st.Push(currentNode.Right);
currentNode = currentNode.Right;
shouldCheckLeft = true;
}
}
}
public void EmptyFlagIsCorectAfterStackBecomesEmpty()
{
var s = new StackViaLinkedList <int>();
s.Push(7);
s.Pop();
Assert.True(s.IsEmpty());
}
// What you get at each level of the recursion tree is a power of 2. Hence, the sum is: 2^0 + 2^1 + 2^2 + ... + 2^{n-1}
// Let O(n) = 1 + 2 + 4 + ... + 2^{n-1}. Then: O(n) - 2*O(n) = 1 - 2^n
// O(n) = 2^n - 1
public void SolveTowerOfHanoi(int n, StackViaLinkedList <int> source, StackViaLinkedList <int> intermediate, StackViaLinkedList <int> destination)
{
if (n > 0)
{
SolveTowerOfHanoi(n - 1, source, destination, intermediate);
Move(source, destination);
SolveTowerOfHanoi(n - 1, intermediate, source, destination);
}
}
public TowerOfHanoi(int numOfPlanks)
{
numberOfPanksOnTower = numOfPlanks;
towerA = new StackViaLinkedList <int>();
for (int i = numberOfPanksOnTower; i >= 1; i--)
{
towerA.Push(i);
}
towerB = new StackViaLinkedList <int>();
towerC = new StackViaLinkedList <int>();
}
public void Push_Test()
{
IStack <char> stack = new StackViaLinkedList <char>();
stack.Push('A');
stack.Push('B');
stack.Push('C');
stack.Push('D');
stack.Push('E');
stack.IsEmpty.Should().BeFalse();
stack.Count.Should().Be(5);
}
static void Main(string[] args)
{
StackViaLinkedList <int> viaLinkedList = new StackViaLinkedList <int>();
int i = 7;
viaLinkedList.Push(i);
viaLinkedList.Push(i * 2);
viaLinkedList.Push(i * 3);
Console.WriteLine(viaLinkedList.Peek());
Console.WriteLine(viaLinkedList.Pop());
}
public void ExercisePushPopPeak()
{
var s = new StackViaLinkedList <int>();
s.Push(5);
Assert.AreEqual(5, s.Peak());
s.Push(45);
s.Push(-34);
Assert.AreEqual(-34, s.Peak());
Assert.AreEqual(-34, s.Pop());
Assert.AreEqual(45, s.Peak());
Assert.AreEqual(45, s.Pop());
Assert.AreEqual(5, s.Peak());
}
public static StackViaLinkedList <int> CreateAStack(int num)
{
// Create the stack
StackViaLinkedList <int> stack = new StackViaLinkedList <int>();
// Populate the unsorted stack
SingleLinkedListNode <int> node = LinkedListHelper.CreateSinglyLinkedList(num);
while (node != null)
{
stack.Push(node.Data);
node = node.NextNode;
}
return(stack);
}
public void reverseStringUsingStack()
{
string str = "abcdefghijklmn";
var s = new StackViaLinkedList <char>();
for (int i = 0; i < str.Length; ++i)
{
s.Push(str[i]);
}
string reversed_string = "";
for (int i = 0; i < str.Length; ++i)
{
reversed_string += s.Pop();
}
Assert.AreEqual("nmlkjihgfedcba", reversed_string);
}
/// <summary>
/// Algo1: 1. Keep a stack and every time a char(other than < or >) is encountered, make stack.top.child = newelement
/// Push this new element into the stack.
/// 2. When a < is encountered, do nothing
/// 3. When a > is encountered, do a pop()
/// </summary>
/// <param name="expression"></param>
/// <returns></returns>
private static TreeNode <char> CreateTreeFromExpression(char[] expression)
{
StackViaLinkedList <TreeNode <char> > stackForTree = new StackViaLinkedList <TreeNode <char> >();
TreeNode <char> headOfTree = null;
for (int expIndex = 0; expIndex < expression.Length; expIndex++)
{
if (expression[expIndex] == '<' || expression[expIndex] == ' ')
{
// No-op
}
else if (expression[expIndex] == '>')
{
SingleLinkedListNode <TreeNode <char> > top = stackForTree.Pop();
if (top == null)
{
throw new Exception("The expression is not well formed");
}
}
else
{
SingleLinkedListNode <TreeNode <char> > top = stackForTree.Peek();
TreeNode <char> currentNode = new TreeNode <char>(expression[expIndex]);
if (top == null)
{
headOfTree = currentNode;
}
else
{
top.Data.Children.Add(currentNode);
}
stackForTree.Push(currentNode);
}
}
// After this step the stack should be empty for a well formed expression
if (stackForTree.Top != null)
{
throw new Exception("The expression is not well formed");
}
return(headOfTree);
}
public void ExceptionThrownOnPeakOnEmptyStack()
{
var s = new StackViaLinkedList <int>();
Assert.Throws <IndexOutOfRangeException>(() => s.Peak());
}
public void NewStackHasCorrectEmptyFlag()
{
var s = new StackViaLinkedList <int>();
Assert.True(s.IsEmpty());
}
public void Move(StackViaLinkedList <int> source, StackViaLinkedList <int> destination)
{
destination.Push(source.Pop());
}
