how to remove duplicate records in the linked list?

the hackerrank post today challenge is to remove duplicate record from integer linklist.

i use hashset to store the unique integer from the linklist, if the current node data already exist in the hashset. i simply pointing the previous node to the current node next pointer. if not found, i add the current node data to the hashset and move to the next node.


here is the sample code in C#

using System;
using System.Collections.Generic;
class Node
{
public int data;
public Node next;
    public Node(int d){
        data=d;
        next=null;
    }
}
class Solution {
  public static Node removeDuplicates(Node head){
    //Write your code here
    if (head==null){
        return null;
    }
    HashSet<int> hashset =new HashSet<int>();
    Node prevNode = head;
    Node currentNode =prevNode.next;
    if(currentNode==null){
        return head;
    }
    hashset.Add(prevNode.data);
    while(currentNode!=null)
        {
        if(hashset.Contains(currentNode.data))
            {
            prevNode.next=currentNode.next;
            currentNode=currentNode.next;
        }
        else{
            hashset.Add(currentNode.data);
              prevNode=currentNode;
            currentNode=currentNode.next;
        }
    }
    return head;
  }
public static  Node insert(Node head,int data)
{
        Node p=new Node(data);
if(head==null)
head=p;
else if(head.next==null)
head.next=p;
else
{
Node start=head;
while(start.next!=null)
start=start.next;
start.next=p;
}
return head;
    }
public static void display(Node head)
{
Node start=head;
while(start!=null)
{
Console.Write(start.data+" ");
start=start.next;
}
}
    static void Main(String[] args) {
Node head=null;
        int T=Int32.Parse(Console.ReadLine());
        while(T-->0){
            int data=Int32.Parse(Console.ReadLine());
            head=insert(head,data);
        }
      head=removeDuplicates(head);
display(head);
}
}

how to use Queue to implement a binary searh true Level Order algorithm?

Currently i had joined the Hackerrank challenag for 30 days

today i got a very interesting topic to use Queue to implement the level Order function

using System; using System.Collections; using System.Collections.Generic; using System.IO; using System.Linq; class Node{ public Node left,right; public int data; public Node(int data){ this.data=data; left=right=null; } } class Solution{ static void levelOrder(Node root){ Queue<Node> nodeQueue=new Queue<Node>(); if(root !=null){ nodeQueue.Enqueue(root); } while(nodeQueue.Count>0){ Node current=nodeQueue.Dequeue(); Console.Write($"{current.data} "); if(current.left !=null){ nodeQueue.Enqueue(current.left); } if(current.right !=null){ nodeQueue.Enqueue(current.right); } } } static Node insert(Node root, int data){ if(root==null){ return new Node(data); } else{ Node cur; if(data<=root.data){ cur=insert(root.left,data); root.left=cur; } else{ cur=insert(root.right,data); root.right=cur; } return root; } } static void Main(String[] args){ Node root=null; int T=Int32.Parse(Console.ReadLine()); while(T-->0){ int data=Int32.Parse(Console.ReadLine()); root=insert(root,data); } levelOrder(root); } }

A simple and stupid PhoneBook in C#

I just completed a HackerRank Challenge today. the topic is about to write a program for a phonebook which allow the user to input contact information and support searching contact by name.

initial i finished it only support number of input search.Finally i have to use the while to support unlimited number of search..


here is the snippet of code. i hope you will enjoy it

using System;
using System.Collections.Generic;
using System.IO;
class Solution {
static void Main(String[] args) {
/* Enter your code here. Read input from STDIN. Print output to STDOUT.
Your class should be named Solution */
Dictionary<string, string> phoneBook=new Dictionary<string, string>();
int totalContact=Int32.Parse(Console.ReadLine());
for(var i=0; i<totalContact; i++){
string input=Console.ReadLine();
string[] strArray=input.Split(null);
if(strArray.Length>=2){
phoneBook.Add(strArray[0], strArray[1]);
}
}
//use the while loop to support unspecific number of search
while(true){
try{
string key=Console.ReadLine();
if (phoneBook.ContainsKey(key))
{
Console.WriteLine($"{key}={phoneBook[key]}");
}
else
{
Console.WriteLine("Not found");
}
}catch(System.Exception ex){
break;
}
}
}
}

cheer