Short Problem Definition: Your teacher has given you the task to draw the structure of a staircase. Being an expert programmer, you decided to make a program for the same. You are given the height of the staircase. Link Staircase Complexity: time complexity is O(N^2) space complexity is O(1) Execution: Either fill each level with N-i empty spaces or adjust to the right. Solution: 1 2 3 4 5 6 7 8...

## HackerRank ‘String Construction’ Solution

Short Problem Definition: Amanda has a string of lowercase letters that she wants to copy to a new string. She can perform the following operations with the given costs. She can perform them any number of times to construct a new string p: Append a character to the end of string p at a cost of 1 dollar. Choose any substring of p and append it to the end of at...

## HackerRank ‘Strong Password’ Solution

Short Problem Definition: Louise joined a social networking site to stay in touch with her friends. The signup page required her to input a name and a password. However, the password must be strong. The website considers a password to be strong if it satisfies the following criteria: Its length is at least 6. It contains at least one digit. It contains at least one...

## HackerRank ‘Save the Prisoner!’ Solution

Short Problem Definition: A jail has N prisoners, and each prisoner has a unique id number,S , ranging from 1 to N. There are M sweets that must be distributed to the prisoners. But wait—there’s a catch—the very last sweet S is poisoned! Can you find and print the ID number of the last prisoner to receive a sweet so he can be warned? Link Save the Prisoner! Complexity: time complexity is O(1)...

## HackerRank ‘Service Lane’ Solution

Short Problem Definition: Calvin is driving his favorite vehicle on the 101 freeway. He notices that the check engine light of his vehicle is on, and he wants to service it immediately to avoid any risks. Luckily, a service lane runs parallel to the highway. The length of the highway and the service lane is N units. The service lane consists of N segments of equal length and different width. Link...

## HackerRank ‘Sherlock and Array’ Solution

Short Problem Definition: Watson gives Sherlock an array A of length N. Then he asks him to determine if there exists an element in the array such that the sum of the elements on its left is equal to the sum of the elements on its right. If there are no elements to the left/right, then the sum is considered to be zero.Formally, find an i, such that, A1+A2…Ai-1 =Ai+1+Ai+2…AN Link Sherlock and...

## HackerRank ‘Sherlock and GCD’ Solution

Short Problem Definition: Sherlock is stuck while solving a problem: Given an array A={a1,a2,..aN}, he wants to know if there exists a subset, B={ai1,ai2,…aik} where 1≤i1<i2<…<ik≤N… Link Sherlock and GCD Complexity: time complexity is O(N); space complexity is O(1) Execution: A subset has no common divisor if the GCD equals 1. There is an interesting fact that leads to my solution: If...

## HackerRank ‘Sherlock and Pairs’ Solution

Short Problem Definition: Sherlock is given an array of N integers A0, A1 … AN-1 by Watson. Now Watson asks Sherlock how many different pairs of indices i and j exist such that i is not equal to j but Ai is equal to Aj. That is, Sherlock has to count total number of pairs of indices (i, j) where Ai = Aj AND i ≠ j. Link Sherlock and Pairs Complexity: time complexity is O(n) space complexity is...

## HackerRank ‘Sherlock and Squares’ Solution

Short Problem Definition: Watson gives two integers A & B to Sherlock and asks if he can count the number of square integers between A and B (both inclusive). A square integer is an integer which is the square of any integer. For example, 1, 4, 9, 16 are some of the square integers as they are squares of 1, 2, 3, 4 respectively. Link Sherlock and Squares Complexity: time complexity is O(sqrt(N));...

## HackerRank ‘Sherlock and The Beast’ Solution

Short Problem Definition: Sherlock Holmes suspects his archenemy, Professor Moriarty, is once again plotting something diabolical. Sherlock’s companion, Dr. Watson, suggests Moriarty may be responsible for MI6’s recent issues with their supercomputer, The Beast. Shortly after resolving to investigate, Sherlock receives a note from Moriarty boasting about infecting The Beastwith a virus; however...