Tuesday, March 21, 2017

Compare two linked lists

Tech host 9:47 AM compare-two-linked-list, frequently-asked-question, interview-question, java, linklist-interview-question, linklist-question, popular-linklist-question No comments

Linked list Interview Question

Compare two linked lists

You’re given the pointer to the head nodes of two linked lists. Compare the data in the nodes of the linked lists to check if they are equal. The lists are equal only if they have the same number of nodes and corresponding nodes contain the same data. Either head pointer given may be null meaning that the corresponding list is empty.

Input Format

You have to complete the int CompareLists(Node* headA, Node* headB) method which takes two arguments - the heads of the two linked lists to compare. You should NOT read any input from stdin/console.

Output Format
Compare the two linked lists and return 1 if the lists are equal. Otherwise, return 0. Do NOT print anything to stdout/console.

Sample Input

NULL, 1 --> NULL
1 --> 2 --> NULL, 1 --> 2 --> NULL

Sample Output

0
1
Explanation 
1. We compare an empty list with a list containing 1. They don't match, hence return 0. 
2. We have 2 similar lists. Hence return 1.

int CompareLists(Node *headA, Node* headB)
{
    int flag=0;
  // This is a "method-only" submission. 
  // You only need to complete this method 
    while(headA!=NULL)
        {
        if(headA->data==headB->data)
            {
            flag=1;
        }
        else
            {
            flag=0;
            break;
        }
        headA=headA->next;
        headB=headB->next;
    }
    if(headB!=NULL)
        {
        flag=0;
    }
    return flag;
}

Note that this approach is not only specific to this type of question you can use this sorting technique in various questions such as if you want to check whether to word are anagrams of one another or not. You can simply sort them and compare them to find out. This approach is also helpful in other questions so i suggest that its better to learn this tricks and keep in mind while attempting the question you may find it useful. You can always search for more coding problems like this to get comfortable to this to approach or you can find new problems where this approach is applicable. So go and search more problems like this and check whether this approach is useful or not and you can tell me about it by commenting and writing about this to me.

Try more and more problems that you find on string and arrays and try to develop an approach the will help you understand problems rather then learning the solution. Once you know how to approach the problem you will able to solve any problem related to strings and array. I wish best of luck to you for your future.

Intersection in a given linked list

Tech host 9:31 AM cracking-the-coding-interview, frequently-asked-question, interview-question, linklist-interview-question, linklist-question, popular-linklist-question No comments

Linked list Interview Question

Intersection in a given linked list

Given pointers to the head nodes of linked lists that merge together at some point, find the Node where the two lists merge. It is guaranteed that the two head Nodes will be different, and neither will be NULL.
In the diagram below, the two lists converge at Node x:

[List #1] a--->b--->c
                     \
                      x--->y--->z--->NULL
                     /
     [List #2] p--->q

Complete the int FindMergeNode(Node* headA, Node* headB) method so that it finds and returns the data value of the Node where the two lists merge.
Input Format
The FindMergeNode(Node*,Node*) method has two parameters, and , which are the non-null head Nodes of two separate linked lists that are guaranteed to converge.
Do not read any input from stdin/console.
Output Format
Each Node has a data field containing an integer; return the integer data for the Node where the two lists converge. Do not write any output to stdout/console.
Sample Input
The diagrams below are graphical representations of the lists that input Nodes and are connected to. Recall that this is a method-only challenge; the method only has initial visibility to those Nodes and must explore the rest of the Nodes using some algorithm of your own design.

Test Case 0

 1
  \
   2--->3--->NULL
  /
 1
Test Case 1

1--->2
      \
       3--->Null
      /
     1
Sample Output

2
3
Explanation

Test Case 0: As demonstrated in the diagram above, the merge Node's data field contains the integer  (so our method should return ). 

Test Case 1: As demonstrated in the diagram above, the merge Node's data field contains the integer  (so our method should return ).


int FindMergeNode(Node *headA, Node *headB)
{
    // Complete this function
    // Do not write the main method.
    int a=0,b=0;
    struct Node* temp = headA;
    while(temp)
        {
        a++;
        temp=temp->next;
    }

    temp = headB;
    while(temp)
        {
        b++;
        
        temp=temp->next;
    }
   
    if(a>b)
        {
        a-=b;
        while(a)
            {
            headA=headA->next;
            a--;
        }
        while(headA==headB)
            {
            headA=headA->next;
             headB=headB->next;
        }
        return headA->data;
    }
    else
        {
        a=b-a;
        while(a!=0)
            {
            
            headB=headB->next;
            a--;
           
        }
        while(!(headA == headB))
            {
           
             headA=headA->next;
             headB=headB->next;
        }
             return headA->data;

    }
    return 0;
}

Reverse of a given linked list

Tech host 9:25 AM cracking-the-coding-interview, frequently-asked-question, interview-question, java, linklist-interview-question, linklist-question, popular-linklist-question No comments

linked list Interview Question

Reverse of a given linked list

You’re given the pointer to the head node of a linked list. Change the next pointers of the nodes so that their order is reversed. The head pointer given may be null meaning that the initial list is empty.

Input Format
You have to complete the Node* Reverse(Node* head) method which takes one argument - the head of the linked list. You should NOT read any input from stdin/console.
Output Format
Change the next pointers of the nodes that their order is reversed and return the head of the reversed linked list. Do NOT print anything to stdout/console.
Sample Input
NULL
2 --> 3 --> NULL

Sample Output
NULL
3 --> 2 --> NULL

Node* Reverse(Node *head)
{
  // Complete this method
    struct Node* prev = NULL;
    struct Node* next = NULL;
    while(head!=NULL)
        {
        next = head->next;
        head->next=prev;
        prev=head;
        head=next;
    }
    head=prev;
    return head;
}

Try more and more problems that you find on string and arrays and try to develop an approach the will help you understand problems rather then learning the solution. Once you know how to approach the problem you will able to solve any problem related to strings and array. I wish best of luck to you for your future.

Insert Node at nth position in a linked list

Tech host 9:19 AM cracking-the-coding-interview, interview-question, java, linklist-interview-question, linklist-question, popular-linklist-question No comments

linked list Interview Question

Insert Node at nth position in a linked list

You’re given the pointer to the head node of a linked list, an integer to add to the list & the position at which the integer must be inserted. Create a new node with the given integer, insert this node at the desired position and return the head node. A position of zero indicates head, a position of 1 indicates one node away from the head and so on. The head pointer given may be null meaning that the initial list is empty.

Input Format

You have to complete the Node Insert(Node* head, int data, int position) method which takes three arguments the head of the linked list, the integer to insert and the position at which the integer must be inserted. You should NOT read any input from stdin/console. position will always be between 0 and the number of the elements in the list.

Output Format
Insert the new node at the desired position and return the head of the updated linked list. Do NOT print anything to stdout/console.
Sample Input
NULL, data = 3, position = 0
3 --> NULL, data = 4, position = 0
Sample Output

3 --> NULL
4 --> 3 --> NULL
Explanation

we have an empty list and position 0. 3 becomes head.
4 is added to position 0, hence 4 becomes head.

Node* InsertNth(Node *head, int data, int position)
{
  // Complete this method only
  // Do not write main function. 
    struct Node* newnode = (struct Node*)malloc(sizeof(struct Node*));
    newnode->data=data;
    newnode->next=NULL;
    struct Node*  ptr = head; 
    if(ptr==NULL)
        {
        head = newnode;
        return head;
    }
    else if(position==0)
        {
        newnode->next=head;
        head=newnode;
        return head;
    }
    else
        {
        while(position>1)
        {   
            ptr=ptr->next;
            position--;
        }
        if(ptr->next==NULL)
        {
            ptr>next=newnode;
        }
        else
        {
            newnode>next=ptr->next;
            ptr->next=newnode;
        }
        return head;
    }
}

linked list Interview Question

Tech host 9:04 AM cracking-the-coding-interview, frequently-asked-question, interview-question, java, linklist-interview-question, linklist-print-a-node, popular-linklist-question No comments

linked list Interview Question

Hey guys i am providing the solution to the most comman linked list question asked in interview as linked list is most important data structure from interview point of view.All these solutions are written by myself and checked for all the possible cases. Please take a look at them and help your self to solve your problems. If you have any query regarding the solutions or you want to ask something leave your comment and i will get back to you as soon as possible. Happy coding.

How to print the node of the given linked list

Tech host 8:50 AM cracking-the-coding-interview, frequently-asked-question, linklist-interview-question, linklist-print-a-node, popular-linklist-question No comments

Linklist Interview Question

How to print the node of the given linked list

If you're new to linked lists, this is a great exercise for learning about them. Given a pointer to the head node of a linked list, print its elements in order, one element per line. If the head pointer is null (indicating the list is empty), don’t print anything.

Input Format
The void Print(Node* head) method takes the head node of a linked list as a parameter. Each struct Node has a data field (which stores integer data) and a next field (which points to the next element in the list).

Note: Do not read any input from stdin/console. Each test case calls the Print method individually and passes it the head of a list.

Output Format
Print the integer data for each element of the linked list to stdout/console (e.g.: using printf, cout, etc.). There should be one element per line.

Sample Input
This example uses the following two linked lists:
NULL
1->2->3->NULL
and are the two head nodes passed as arguments to Print(Node* head).

Note: In linked list diagrams, -> describes a pointer to the next node in the list.

Sample Output

1
2
3
Explanation

Test Case 0: NULL. An empty list is passed to the method, so nothing is printed.

Test Case 1: 1->2->3->NULL. This is a non-empty list so we loop through each element and printing each element's data field on its own line.

Here i am only providing the main function you have to create the link list first then only you can print its nodes.

/*
  Print elements of a linked list on console 
  head pointer input could be NULL as well for empty list
  Node is defined as 
  struct Node
  {
     int data;
     struct Node *next;
  }
*/
void Print(Node *head)
{
  // This is a "method-only" submission. 
  // You only need to complete this method. 
    while(head!=NULL)
        {
        cout<<head->data<<endl;
        head = head->next;
    }
}

Array Left Rotation

Tech host 8:34 AM array, array-interview-question, array-left-rotation, frequently-asked-question, interview-question, java, left-rotation No comments

Array Interview Question

Hacker Rank Question

Array Left Rotation

Hey guys i am providing the solutions for the question given in the Chapter one Arrays and String of the very famous book Cracking the coding interview. All these solutions are written by myself and checked for all the possible cases. Please take a look at them and help your self to solve your problems. If you have any query regarding the solutions or you want to ask something leave your comment and i will get back to you as soon as possible. Happy coding.

A left rotation operation on an array of size shifts each of the array's elements unit to the left. For example, if left rotations are performed on array , then the array would become .
Given an array of integers and a number, , perform left rotations on the array. Then print the updated array as a single line of space-separated integers.
Input Format
The first line contains two space-separated integers denoting the respective values of (the number of integers) and (the number of left rotations you must perform). The second line contains space-separated integers describing the respective elements of the array's initial state.
Constraints
Output Format
Print a single line of space-separated integers denoting the final state of the array after performing left rotations.
Sample Input
5 4
1 2 3 4 5
Sample Output
5 1 2 3 4
Explanation
When we perform left rotations, the array undergoes the following sequence of changes:
Thus, we print the array's final state as a single line of space-separated values, which is 5 1 2 3 4.

import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) throws IOException{
        /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        String as[]  =br.readLine().split("\\s");
        int n = Integer.parseInt(as[0]);
        int r = Integer.parseInt(as[1]);
        int c;
        String ele[] = br.readLine().split("\\s");
        ArrayList <Integer> arr = new ArrayList <Integer> ();
        for(int i=0;i<n;i++)
            {
             c = Integer.parseInt(ele[i]);
            arr.add(c);
        }
        for(int j=0;j<r;j++)
            {
             c = arr.remove(0);
            arr.add(c);
        }
        ListIterator <Integer> itr = null;
        itr  = arr.listIterator();
        while(itr.hasNext()){
       System.out.print(itr.next()+" ");
        }
    }
}

Arrays-String interview question 8

Tech host 2:14 AM array, array-interview-question, cracking-the-coding-interview, frequently-asked-question, interview-question, popular-string-question, string, string-interview-question, string-palindrome-question No comments

Cracking the coding interview

Arrays and String solutions

Question 8

Zero Matrix: Write an algorithm such that if an element in an MxN matrix is 0, its entire row and column are set to O.
Solution: You can find the solution for this problem here.
Solution 1 using java.
In this problem we are setting the elements in the particular column and row to zero if any element in that particular row or column is already zero initially. Here first we have to check which of the elements are initially zero in the matrix and save their row and column number in an array then we write a function to make all the elements of the particular row to zero and another function to make all the elements of the particular column to zero.

So we have to write 3 functions
To find the elements that are zero and and note their row and column in which they occur.
next we have to write the function that make all the element of a particular row zero.
and last function that make all the elements in the particular column to zero.
This problem is very unique and easy as well just need a focus mind and little practice to solve this problem.

import java.util.*;
import java.lang.*;
import java.io.*;
/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
public static void main (String[] args) throws java.lang.Exception
{
// your code goes here
int matrix[][]={{1,2,3},{4,5,6},{7,8,0}};
array(matrix);
for(int i=0;i<matrix.length;i++)
  {
   for(int j=0;j<matrix[0].length;j++)
   {
    System.out.print(matrix[i][j]);
   }
   System.out.println("");
  }
 }
 public static void array(int a[][])
 {
  int[] row = new int[a.length];
  int[] col = new int[a[0].length];
  int i=0,j=0;
  for(i=0;i<a.length;i++)
  {
   for(j=0;j<a[0].length;j++)
   {
    if(a[i][j]==0)
    {
     row[i]=1;
     col[j]=1;
    }
   }
  }
  //row nullfy
  for(i=0;i<row.length;i++)
  {
   if(row[i]==1)
   {
    for(j=0;j<a[i].length;j++)
    {
     a[i][j]=0;
    } 
   }
  }
  //column nullfy
  for(i=0;i<col.length;i++)
  {
   if(col[i]==1)
   {
    for(j=0;j<a.length;j++)
    {
     a[j][i]=0;
    } 
   } 
  }
 }
}

Note that this approach is not only specific to this type of question you can use this sorting technique in various questions such as if you want to check whether to word are anagrams of one another or not. You can simply sort them and compare them to find out. This approach is also helpful in other questions so i suggest that its better to learn this tricks and keep in mind while attempting the question you may find it useful. You can always search for more coding problems like this to get comfortable to this to approach or you can find new problems where this approach is applicable. So go and search more problems like this and check whether this approach is useful or not and you can tell me about it by commenting and writing about this to me.
Try more and more problems that you find on string and arrays and try to develop an approach the will help you understand problems rather then learning the solution. Once you know how to approach the problem you will able to solve any problem related to strings and array. I wish best of luck to you for your future.

Arrays-String interview question 7

Tech host 1:37 AM array, array-interview-question, cracking-the-coding-interview, frequently-asked-question, interview-question, popular-string-question, string, string-interview-question, string-palindrome-question No comments

Cracking the coding interview

Arrays and String solutions

Question 7

Rotate Matrix: Given an image represented by an NxN matrix, where each pixel in the image is 4 bytes, write a method to rotate the image by 90 degrees. (an you do this in place?

Solution

You can find the solution for this problem here.
Solution 1 using  java.

This problem is the most asked problem of all.This problem looks easy but it is very tricky to solve as you have to make a general function for the rotation of the matrix. As will all know that matrix can be rotated in either clockwise direction or anti-clockwise direction. Here i have written a function that rotates the matrix in the anti-clockwise direction by 90 degrees.

Lets see how the rotation is taking place here
First store the first element of the matrix in the temp variable and then is replaced it with the bottom left element of the matrix.
Then replace the bottom left element of the matrix with the bottom right element of the matrix.
Moving on replace the bottom right element of the matrix with the top right element of the matrix.
Then replace the top right with the value stored in the temp variable.
Make sure to carefully use the indexing for the row and col of the matrix as the tends to change as the loop runs.
and also consider the inner matrix rotation while writing the program and for get correct result i suggest that you consider 4x4 matrix as an example.

If we have to talk about the complexity of this function then it is n square as we have to touch ever element twice in the matrix. import java.util.*; import java.lang.*; import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
 public static void main (String[] args) throws java.lang.Exception
 {
  int matrix[][]={{10,11,12,13},{14,15,16,17},{18,19,20,21},{22,23,24,25}};
  //int matrix[][]={{12,13,14},{15,16,17},{18,19,20}};
  array(matrix);
  for(int i=0;i<matrix.length;i++)
  {
   for(int j=0;j<matrix[0].length;j++)
   {
    System.out.print(matrix[i][j]+" ");
   }
   System.out.println("");
  }
 }
 public static void array(int arr[][])
 {
  int n=arr.length;
  for(int i=0;i<arr.length/2;i++)
  {
   int x=n-1-i;
   for(int j=i;j<x;j++)
   {
    int temp = arr[i][j];
    arr[i][j]=arr[n-1-j][i];
    arr[n-1-j][i]=arr[n-1-i][n-1-j];
    arr[n-1-i][n-1-j]=arr[j][n-1-i];
    arr[j][n-1-i]=temp;
   }
  } 
 }

}

Arrays-String interview question 6

Tech host 6:13 AM array, array-interview-question, cracking-the-coding-interview, frequently-asked-question, interview-question, popular-string-question, string, string-interview-question, string-palindrome-question No comments

Cracking the coding interview

Arrays and String solutions

Question 6

String Compression: Implement a method to perform basic string compression using the counts of repeated characters. For example, the string aabcccccaaa would become a2b1c5a3. If the "compressed" string would not become smaller than the original string, your method should return the original string. You can assume the string has only uppercase and lowercase letters (a - z).

Solution
You can find the solution for this problem here.
Solution 1 using java.
This problem is very unique and rarely asked in the interview question but it is always good to learn as much as you can and to prepare for the worst to achieve good things.In this problem you have to remove the repeating characters from the and string and place the number which is equal to the occurrence of that character which in turn reduces the length of the string with keep all the information about the string such as no of times character appearing in the string. But in this process a unique case might occur were the length of the compressed string is larger then the actual string in that case we have to give original strong not the compressed string because our aim is to reduce the length of the string let us understand with an example suppose if a given string is abcdefgh then the compressed sting of this string will be a1b1c1d1e1f1g1h1 as we can see that the length of the compressed string is more then the original string so we have to take care of this case also and write a program that handles this case also.

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class Ideone
{
 public static void main (String[] args) throws java.lang.Exception
 {
  // your code goes here
  System.out.println(compress());
 }
 public static String compress()
 {
       String a="aaaaaaaabbbbbbbccccccccccccccccccddddddddddddddeeeeeeeeee";
         int ctr=0;
  StringBuilder b = new StringBuilder(a.length());
  for(int i=0;i=a.length()||a.charAt(i)!=a.charAt(i+1))
   {
    b.append(a.charAt(i));
    b.append(String.valueOf(ctr));
    ctr=0;
   }   
  }
  return b.length()>a.length()?a:b.toString();
 }
}

Tuesday, March 21, 2017

Linked list Interview Question

Compare two linked lists

Wednesday, March 15, 2017

Linked list Interview Question

Intersection in a given linked list

linked list Interview Question

Reverse of a given linked list

linked list Interview Question

Insert Node at nth position in a linked list

linked list Interview Question

Question 1 Print the nodes of the given linked list?

Question 2 Insert the nodes at the given position in linked list?

Question 3 Find the intersection in a given linked list?

Question 4 Reverse a linked list?

Question 5 Compare two linked list

Linklist Interview Question

How to print the node of the given linked list

Array Interview Question

Hacker Rank Question

Array Left Rotation

Sunday, March 5, 2017

Cracking the coding interview

Arrays and String solutions

Question 8

Cracking the coding interview

Arrays and String solutions

Question 7

Saturday, March 4, 2017

Cracking the coding interview

Arrays and String solutions

Question 6

Blog Archive

Popular Posts

Categories

About Me

Label

Question 1
Print the nodes of the given linked list?

Question 2
Insert the nodes at the given position in linked list?

Question 3
Find the intersection in a given linked list?

Question 4
Reverse a linked list?

Question 5
Compare two linked list