HackerRank Problem and Solutions

The repository contains the solutions to various HackerRank problems solved using C++ programmming language. Each solution includes a reference to the problem statement and is well-documented to explain the logic and approach. Below you can find the documentation of 10 different problems.

1. camelCase

Problem Explanation:

The problem is to calculate the number of words in a string s which is a combination of n number of words.

Solution Approach:

Here, we are considering a string as a combination of words.

In a camel case format, the first word starts with a small letter and other words start with a capital letter.

In this problem, we have to count the number of capital letters in the string as each words start with a capital letter that corresponds to the number of words.

Initilise count = 1 as each string has atleast one word.

Create a loop to traverse through the string to calculate the number of capital letters that corresponds to the number of words.

Return the count

Sample Input to the function

camelCase

Sample Output to the function

2. Pangram

Problem Explanation:

The problem is to check if the given string contains all the letters of the alphabet.

Solution Approach:

A string is called pangram if it contains all the letters of the alphabet

Define a boolean array of size 26 and set all the values to false as default.

To get the letter number of each character from the string

Convert each characters to lower case

Store it to an integer number after subtracting the currrent value from alphabet 'a'

Traverse through the entire string and change the positions were the character exist to "true"

Finally, check through the boolean array if any position is false. If so, it is not pangram. If all the values are true, it is a pangram

Sample Input to the function

We promptly judged antique ivory buckles for the next prize

Sample Output to the function

pangram

3. Max Min

Problem Explanation:

The problem is to calculate the least difference between the maximum value and the minimum value of a subarray of size k from an array arr

Solution Approach:

First, we sort the array.

Then store the minimum and the maximum value from the sorted array

Minimum value will be the first term

Maximum value will be the k-1 th term

Now their difference should be minimum from the other subarrays.

So as they are sorted, the min and max value are traversed till the max value reaches the end of the array.

And each time they check if thier difference is the minimum. An return the most min value.

Sample Input to the function

4   //n=4
2   //k=2
1
4
7
2

Sample Output to the function

4. Sherloack and Array

Problem Explanation:

The problem is to find an element in an array such that the sum of all elements to the left is equal to the sum of all elements to the right of that element. If such an element exist print "YES" else "NO"

Solution Approach:

Initialise left and right variable to zero and find the sum of all the elements of the array

Now traverse throught the array. For the first element,

left = 0

right = sum - 1st element

Now check if left and right is equal. If not traverse to the next element.

As we move through the array, each term keeps decreasing in the right and the previous elements is added to the left.

Sample Input to the function

1 2 3 3

Sample Output to the function

YES

5. Pairs

Problem Explanation:

The problem is to find the number of pairs of array elements that have a difference equal to the k

Solution Approach:

2 pointers are initialised

Initally i pointer is set to zero and the next pointer j traverses through the array from i+1

There is a counter that counter the number of pairs where the difference between the values fron the pointer i and j is the given value k

After j traverses the whole array, i moves to the next value and j starts again fro i+1

Sample Input to the function

5 2  // n=5, k=2       
1 5 3 4 2

Sample Output to the function

6. Mars Exploration

Problem Explanation:

A series of "SOS" messages are send. The problem is to find the number of changed letters in the SOS messages when received.

Solution Approach:

Here, SOS is of 3 letters. So after finding the lenght of the array, divide it by 3 to find the number of sets of "SOS" messages.

After which, traverse through each number of sets and in each set,

Check if the letters in the 0 and 2 th positions are 'S' or not. If not increment the counter for the numbers of faults in the received message.

And check if the letter in the 1st position is 'O' or not. If not increment the counter for the numbers of faults in the received message.

After traversing through the whole array, return the count.

Sample Input to the function

SOSSOTSOSSSS

Sample Output to the function

7. HackerRank in a String!

Problem Explanation:

The problem is to check if the word "hackerrank" is present in the given string in the correct subsequent order.

Solution Approach:

Intialise a string as "hackerrank"

Now traverse through the given string and check if each letter of the hackerrank string is present in the given string one by one.

Therefore also checking igf they are in the right order as well

Once the first letter of hackerrank is found the given string, the pointer moves to the next letter of hackerrank while the pointer in the array keeps traversing until it find a match.

Then the hackerrank pointer moves tot he next pointer and the search continues.

Sample Input to the function

hhhaaaccckkkkerrrrannkk

Sample Output to the function

YES

8. Lonely Integer

Problem Explanation:

The problem is to find the unique element where all the other elements in the array occur twice.

Solution Approach:

Intially sort the array

Now the if we traverse through the array, the term and next term should be equal if its not a unique number

If that condition fails, the term is unique.

There is an edge case,

If the unique number is at the end, check if the last term and the second last term is equal

If not, that is the unique number

Sample Input to the function

Sample Output to the function

9. Stock Maximize

Problem Explanation:

The problem is to calculate the sum of all maximum profits when stocks are bought and sold in the mentioned array values.

Solution Approach:

Intially the selling pricing and max profit to zero

Now, traverse through the array

Each time check if the current price is greater than the selling price set. If so, change the selling price to the current value

And while traversing, calculate if there is any profit as a sum while traversing through the array. An return the max profit

Sample Input to the function

Sample Output to the function

10. New Year Chaos

Problem Explanation:

The problem is to calculate the minimum number of swaps called bribes that took place to get to a given queue order in the given array. If the number of swaps by the element is greated than 2, return "Too chaotic"

Solution Approach:

Intially traverse through the array

check if each value is in a uniform progression

if not, atleast it is with a difference of 2 otherwise return "Too chaotic"

Now, we need to return the number swaps from the original order to acheive the current orderof the given array

To calculate that, we compare max 2 term before gratually with the current terms.

If it is swapped, it is greater. Therefore the swapped count increases.

Also a simple condition is also kept to not cross 0th index as we are starting from the last index and traversing to calculate the number of swaps

HackerRank Problem and Solutions

1. camelCase

Problem Explanation:

Solution Approach:

Sample Input to the function

Sample Output to the function

2. Pangram

Problem Explanation:

Solution Approach:

Sample Input to the function

Sample Output to the function

3. Max Min

Problem Explanation:

Solution Approach:

Sample Input to the function

Sample Output to the function

4. Sherloack and Array

Problem Explanation:

Solution Approach:

Sample Input to the function

Sample Output to the function

5. Pairs

Problem Explanation:

Solution Approach:

Sample Input to the function

Sample Output to the function

6. Mars Exploration

Problem Explanation:

Solution Approach:

Sample Input to the function

Sample Output to the function

7. HackerRank in a String!

Problem Explanation:

Solution Approach:

Sample Input to the function

Sample Output to the function

8. Lonely Integer

Problem Explanation:

Solution Approach:

Sample Input to the function

Sample Output to the function

9. Stock Maximize

Problem Explanation:

Solution Approach:

Sample Input to the function

Sample Output to the function

10. New Year Chaos

Problem Explanation:

Solution Approach:

Sample Input to the function

Sample Output to the function

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