public static void Main(string[] args)
{
StackLinkedList <string> stackLinkedList = new StackLinkedList <string>();
Console.WriteLine($"Size: {stackLinkedList.Size()}");
Console.WriteLine($"IsEmpty: {stackLinkedList.IsEmpty()}");
Console.WriteLine();
stackLinkedList.Push("John");
stackLinkedList.Push("Sarah");
stackLinkedList.Push("Mario");
Console.WriteLine();
Console.WriteLine($"Size: {stackLinkedList.Size()}");
Console.WriteLine($"IsEmpty: {stackLinkedList.IsEmpty()}");
Console.WriteLine();
Console.WriteLine($"Pop: {stackLinkedList.Pop().ToString()}");
Console.WriteLine($"Peek: {stackLinkedList.Peek().ToString()}");
Console.WriteLine($"Pop: {stackLinkedList.Pop().ToString()}");
Console.WriteLine($"Peek: {stackLinkedList.Peek().ToString()}");
Console.WriteLine();
Console.WriteLine($"Size: {stackLinkedList.Size()}");
// Expected Output
// ------------------
// Size: 0
// IsEmpty: True
//
// Push: John
// Push: Sarah
// Push: Mario
//
// Size: 3
// IsEmpty: False
//
// Pop: Mario
// Peek: Sarah
// Pop: Sarah
// Peek: John
//
// Size: 1
}
public void IsEmpty_EmptyStackShouldReturnTrue()
{
// Arrange
StackLinkedList <int> sut = new StackLinkedList <int>();
bool expected = true;
// Act
bool actual = sut.IsEmpty();
// Assert
Assert.Equal(expected, actual);
}
public void Clear_ClearStackWithTwoNumbersShouldWork()
{
// Arrange
StackLinkedList <int> sut = new StackLinkedList <int>();
bool expected = true;
// Act
sut.Add(int.MaxValue);
sut.Add(int.MinValue);
sut.Clear();
bool actual = sut.IsEmpty();
// Assert
Assert.Equal(expected, actual);
}
/// <summary>
/// Depth-first search (DFS) is an algorithm for traversing or searching tree or graph data structures.
/// Finds all vertices that can be reached by the starting vertex.
/// </summary>
/// <param name="rootVertex"></param>
/// <param name="previsit"></param>
/// <returns></returns>
public HashSet <T> DepthFirstSearch(T rootVertex, Action <T> preVisit = null)
{
// Traversed graph information
var visitedVerticesInfo = new HashSet <T>();
if (!_aList.ContainsKey(rootVertex))
{
return(visitedVerticesInfo);
}
// Create a stack and add root vertex
var stack = new StackLinkedList <T>();
stack.Push(rootVertex);
// As long as the stack is not empty:
while (!stack.IsEmpty())
{
// Repeatedly pop a vertex u from the queue.
var vertex = stack.Pop();
// Ignore if neigbor is already visited
if (visitedVerticesInfo.Contains(vertex))
{
continue;
}
// Trace the path
preVisit?.Invoke(vertex);
// Add vertex info to the visited list
visitedVerticesInfo.Add(vertex);
// For each neighbor v of u that has not been visited:
foreach (var neighbor in _aList[vertex])
{
if (!visitedVerticesInfo.Contains(neighbor))
{
// Push v
stack.Push(neighbor);
}
}
}
return(visitedVerticesInfo);
}