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 ‘Sherlock and Watson’ Solution

Short Problem Definition: John Watson performs an operation called Right Circular Rotation on an integer array [a0, a1, … an-1]. Right Circular Rotation transforms the array from [a0, a1, … aN-1] to [aN-1, a0,… aN-2]. He performs the operation K times and tests Sherlock’s ability to identify the element at a particular position in the array. He asks Q queries. Each query consists of one integer...

## 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...

## HackerRank ‘Song of Pi’ Solution

Short Problem Definition: That’s the value of pi! (Ignoring the floating point) A song is a pi song if the length of its words represent the value of pi. Link Song of Pi Complexity: time complexity is O(N*T) space complexity is O(N) Execution: This problem is straight forward. Solution: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 #!/usr/bin/py PI = map(int...

## HackerRank ‘Simple Text Editor’ Solution

Short Problem Definition: In this problem, your task is to implement a simple text editor. Initially, a file contains an empty string S. Your task is to perform Q operations consisting of the following 4 types: append(W) – Appends the string W at the end of S. erase(k) – Erase the last k character of S. get(k) – Returns the kth character of S. undo() – Undo the last not previously undone...

## HackerRank ‘Picking Numbers’ Solution

Short Problem Definition: Given an array of integers, find and print the maximum number of integers you can select from the array such that the absolute difference between any two of the chosen integers is less than or equal to 1. For example, if your array is a = [1, 1, 2, 2, 4, 4, 5, 5, 5], you can create two subarrays meeting the criterion: [1 ,1 ,2 ,2] and [4, 4, 5, 5, 5]. The...

## HackerRank ‘Palindrome Index’ Solution

Short Problem Definition: You are given a string of lower case letters. Your task is to figure out the index of the character on whose removal it will make the string a palindrome. There will always be a valid solution. Link Palindrome Index Complexity: time complexity is O(N) space complexity is O(N) Execution: The solution seems n^2 but isPalindrome is executed only once. Due to the problem...

## 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...

## HackerRank ‘Poisonous Plants’ Solution

Short Problem Definition: There are NN plants in a garden. Each of these plants has been added with some amount of pesticide. After each day, if any plant has more pesticide than the plant at its left, being weaker than the left one, it dies. You are given the initial values of the pesticide in each plant. Print the number of days after which no plant dies, i.e. the time after which there are no...

## HackerRank ‘Plus Minus’ Solution

Short Problem Definition: You’re given an array containing integer values. You need to print the fraction of count of positive numbers, negative numbers and zeroes to the total numbers. Print the value of the fractions correct to 3 decimal places. Link Plus Minus Complexity: time complexity is O(N) space complexity is O(1) Execution: Count the values. Do not forget to force floats instead of...