Sunday, March 25, 2007

Tree Data structure in C Sharp .NET

Here is a simple Tree data structure in C sharp.NET


using System;
using System.Collections.Generic;
using System.Text;

namespace Algorithms
{
class Tree
{
private TreeNode root;
public Tree()
{
root = null;
}

public TreeNode FindRecursive(TreeNode root, int dataValue)
{
if (root == null)
{ return null; }
else if (root.DataValue == dataValue)
{ return root; }
else if (root.DataValue < dataValue)
{ return FindRecursive(root.RightNode, dataValue);}
else
{ return FindRecursive(root.LeftNode, dataValue);
}
}
public TreeNode Find(int dataValue)
{
if (root == null)
{
return null;
}
else
{
TreeNode currentNode = root;
while (currentNode != null)
{
if (currentNode.DataValue == dataValue)
{
return currentNode;
}
else if (currentNode.DataValue < dataValue)
{
currentNode = currentNode.RightNode;
}
else if (currentNode.DataValue > dataValue)
{
currentNode = currentNode.LeftNode;
}
return null;
}
return null;
}
}
}
public class TreeNode
{
private int dataValue;
private TreeNode leftNode = null;
private TreeNode rightNode = null;

public TreeNode(int data)
{
dataValue = data;
}
public TreeNode LeftNode
{
get
{
return leftNode;
}
set
{
leftNode = value;
}
}
public TreeNode RightNode
{
get
{
return rightNode;
}
set
{
rightNode = value;
}
}
public int DataValue
{
get
{
return dataValue;
}
set
{
dataValue = value;
}
}

}
}

Sunday, February 25, 2007

Check If Cycle exists in a Linked List

Check if the linked list contains a cycle


using System;
using System.Collections.Generic;
using System.Text;

namespace Algorithms
{
public class LinkedList
{
private Node head;

public LinkedList()
{
head = null;
}


public bool CheckCycle()
{
Node step1Node = head;
Node step2Node = head.NextNode;

while (true)
{
if ((step2Node == null)||(step2Node.NextNode == null))
return false;
else if ((step1Node.Equals(step2Node))||(step1Node.Equals(step2Node.NextNode)))
return true;
else
{
step2Node = step2Node.NextNode;
step2Node = step2Node.NextNode;
step1Node = step1Node.NextNode;
}
}
}
public int FindPosition(int data)
{
Node checkNode = head;
int position = 1;
int dataPosition = 0;
while (checkNode != null)
{
if (checkNode.DataValue == data)
{
dataPosition = position;
}
checkNode = checkNode.NextNode;
position = position + 1;
}
return dataPosition;

}
}
public class Node
{
private int dataValue;
private Node nextNode = null;

public Node(int data)
{
dataValue = data;
}
public Node NextNode
{
get
{
return nextNode;
}
set
{
nextNode = value;
}
}
public int DataValue
{
get
{
return dataValue;
}
set
{
dataValue = value;
}
}

}
}

Nth Element from the last in a Linked List

Another advanced algorithm is to find the Nth Element from the LAST with the optimal performance.
Here is the implementation


using System;
using System.Collections.Generic;
using System.Text;

namespace Algorithms
{
public class LinkedList
{
private Node head;

public LinkedList()
{
head = null;
}

public int FindNthElementFromLast(int m)
{
int n = m - 1;
int returnValue = -1;
if (n >= 0)
{
Node nthElement = head;
Node currentElement = head;
for (int i =0;i less than n;i++)
{
if (currentElement.NextNode != null)
{
currentElement = currentElement.NextNode;
}
else
{
returnValue = -1;
return returnValue;
}
}

if (returnValue != -1)
{
while (currentElement.NextNode != null)
{
currentElement = currentElement.NextNode;
nthElement = nthElement.NextNode;
}
returnValue = nthElement.DataValue;
}
}
return returnValue;

}

}
public class Node
{
private int dataValue;
private Node nextNode = null;

public Node(int data)
{
dataValue = data;
}
public Node NextNode
{
get
{
return nextNode;
}
set
{
nextNode = value;
}
}
public int DataValue
{
get
{
return dataValue;
}
set
{
dataValue = value;
}
}

}
}

Linked List SORT Algorithm

If you need a sort algorithm in Linked List. Please check other implementation in my last blog.


using System;
using System.Collections.Generic;
using System.Text;

namespace Algorithms
{
public class LinkedList
{
private Node head;

public LinkedList()
{
head = null;
}

public void Sort()
{
if (head != null)
{
int j = 0;
Node MinElement = head;
Node currentElement = MinElement.NextNode;
while (currentElement != null)
{

if (currentElement.DataValue < MinElement.DataValue)
{
MinElement = currentElement;
Insert(MinElement.DataValue);
DeleteAtPosition(j+1);
}
MinElement = MinElement.NextNode;
}
}
}

}
public class Node
{
private int dataValue;
private Node nextNode = null;

public Node(int data)
{
dataValue = data;
}
public Node NextNode
{
get
{
return nextNode;
}
set
{
nextNode = value;
}
}
public int DataValue
{
get
{
return dataValue;
}
set
{
dataValue = value;
}
}

}
}

Saturday, January 20, 2007

Linked List in C Sharp.NET

I got tones of emails, lately for Linklist and Tree data structure implemetation

Here is a simple Linked List Data structure in C Sharp.NET. A LinkedList will always have two class a LinkedList class and a Node Class.
I have also included most common options to insert and Delete nodes.


using System;
using System.Collections.Generic;
using System.Text;

namespace Algorithms
{
public class LinkedList
{
private Node head;

public LinkedList()
{
head = null;
}
public void Insert(int dataValue)
{
if (head == null)
{
Node nodeInsert = new Node(dataValue);
head = nodeInsert;
nodeInsert.NextNode = null;
}
else
{
Node nodeInsert = new Node(dataValue);
nodeInsert.NextNode = head;
head = nodeInsert;
}
}
public void InsertAtPosition(Node insertNode, int i)
{
if (i == 0)
{
insertNode.NextNode = head;
head = insertNode;
}
else
{
Node currentNode = head;
Node currentNodeNext = head.NextNode;
for (int j = 0; j < i; j++)
{
currentNode = currentNode.NextNode;
currentNodeNext = currentNode.NextNode;
}
if (currentNode != null)
{
currentNode.NextNode = insertNode;
insertNode.NextNode = currentNodeNext;
}


}
}
public void DeleteAtPosition(int i)
{
if (i == 0)
{
head = null;
}
else
{
Node currentNode = head;
Node currentNodeNext = head.NextNode;
for (int j = 0; j < i; j++)
{
currentNode = currentNode.NextNode;
currentNodeNext = currentNode.NextNode;
}
if (currentNode != null)
{
currentNode.NextNode = currentNodeNext.NextNode;
}
}
}
public bool Delete(Node nodeToDelete)
{
bool returnFlag = false;

if (head == null)
returnFlag = false;
else if (head.Equals(nodeToDelete))
{
head = null;
returnFlag = true;
}
else
{
Node checkNode = head;
Node checkNodeNext = head.NextNode;
while (checkNodeNext != null)
{
if (checkNodeNext.Equals(nodeToDelete))
{
checkNode.NextNode = checkNodeNext.NextNode;
checkNodeNext = null;
returnFlag = true;
}
}
}
return returnFlag;

}
public void Print()
{
Node firstNode = head;
while (firstNode != null)
{
Console.Write(firstNode.DataValue + " ");
firstNode = firstNode.NextNode;
}
}
public void Clear()
{
Node checkNode = head;
Node checkNodeNext;

while (checkNode != null)
{
checkNodeNext = checkNode.NextNode;
checkNode = null;
checkNode = checkNodeNext;
}

}

}
public class Node
{
private int dataValue;
private Node nextNode = null;

public Node(int data)
{
dataValue = data;
}
public Node NextNode
{
get
{
return nextNode;
}
set
{
nextNode = value;
}
}
public int DataValue
{
get
{
return dataValue;
}
set
{
dataValue = value;
}
}

}
}

Monday, December 25, 2006

First Non-Repeated Character from a UNICODE String using Hash Table

the only difference here is the input string can be UNICODE (65000 characters) instead of ASCII Code (256 characters) so using a hash table makes more sense


public static char FirstNonRepeatedHash(string stringToCheck)
{
Hashtable cHash = new Hashtable();
int length = stringToCheck.Length;
int i = 0;
bool hashPresent = false;
char charToReturn = '\0';

for (i = 0; i < length; i++)
{
hashPresent = cHash.Contains(stringToCheck[i]);
if (hashPresent)
{
cHash[stringToCheck[i]] = 1 + Convert.ToInt32(cHash[stringToCheck[i]]);
}
else
{
cHash.Add(Convert.ToChar(stringToCheck[i]), 1);
}

}

for (i = 0; i < length; i++)
{
if (Convert.ToInt32(cHash[stringToCheck[i]]) ==1 )
{
charToReturn = stringToCheck[i];
break;
}
}
return charToReturn;
}

First Non repeated Character in a String using an Array

Here is how to find the first non repeated character in an a string using an array
the assumption is the String is ASCII other wise check for the hash table function

For example If the input is "TEETOTALAR" The First non repeated Character is "O"


public static char FirstNonRepeatedArray(string stringToCheck)
{
int length = stringToCheck.Length;
int i = 0;
int[] intCollection = new int[256];
char returnChar = '\0';

for (i = 0; i < length; i++)
{
intCollection[stringToCheck[i]] = intCollection[stringToCheck[i]] + 1;
}
for (i = 0; i < length; i++)
{
if (intCollection[stringToCheck[i]] == 1)
{
returnChar = stringToCheck[i];
break;
}
}
return returnChar;
}