Short Problem Definition: The Utopian Tree goes through 2 cycles of growth every year. The first growth cycle occurs during the spring, when it doubles in height. The second growth cycle occurs during the summer, when its height increases by 1 meter. Â Now, a new Utopian Tree sapling is planted at the onset of spring. Its height is 1 meter. Can you find the height of the tree after N growth cycles...

## HackerRank âWaiterâ Solution

Short Problem Definition: You are a waiter at a party. There are NN stacked plates. Each plate has a number written on it. You start picking up the plates from the top one by one and check whether the number written on the plate is divisible by a primeâŚ. Link Waiter Complexity: time complexity isÂ O(N*Q) space complexity is O(N) Execution: First of all, generate primes using Sieve, or copy-paste a...

## HackerRank âWeighted Uniform Stringsâ Solution

Short Problem Definition: A weighted string is a string of lowercase English letters where each letter has a weight. Character weights are 1 to 26 from a to zâŚ Link Weighted Uniform String Complexity: time complexity is O(N) space complexity is O(N) Execution: Parsing the string for every query is suboptimal, so I first preprocess the string. Now we know that uniform...

## HackerRank âPlus Minusâ Solution

Short Problem Definition: Youâre 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...

## HackerRank âPoisonous Plantsâ 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 âRepeated Stringâ Solution

Short Problem Definition: Lilah has a string, s, of lowercase English letters that she repeated infinitely many times. Given an integer, n, find and print the number of letters a in the first n letters of Lilahâs infinite string. For example, if the string s = âabcacâ and n = 10, the substring we consider is abcacabcac, the first 10 characters of her infinite string. There...

## HackerRank âSave the Prisoner!â 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 waitâthereâs a catchâthe 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 âService Laneâ 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 âSherlock and Arrayâ 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+A2âŚAi-1 =Ai+1+Ai+2âŚAN Link Sherlock and...

## HackerRank âSherlock and GCDâ 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,âŚaik} where 1â¤i1<i2<âŚ<ikâ¤NâŚ 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...