Alice has a binary string. She thinks a binary string is beautiful if and only if it doesn't contain the substring . In one step, Alice can change a to a or vice versa. Count and print the minimum number of steps needed…
You are given a string containing characters and only. Your task is to change it into a string such that there are no matching adjacent characters. To do this, you are allowed to delete zero or more characters in the…
John has collected various rocks. Each rock has various minerals embeded in it. Each type of mineral is designated by a lowercase letter in the range . There may be multiple occurrences of a mineral in a rock. A mineral…
Steve has a string of lowercase characters in range ascii[‘a’..’z’]. He wants to reduce the string to its shortest length by doing a series of operations. In each operation he selects a pair of adjacent lowercase…
In this challenge, you will determine whether a string is funny or not. To determine whether a string is funny, create a copy of the string in reverse e.g. . Iterating through each string, compare the absolute…
Roy wanted to increase his typing speed for programming contests. His friend suggested that he type the sentence "The quick brown fox jumps over the lazy dog" repeatedly. This sentence is known as a pangram because it…
We say that a string contains the word hackerrank if a subsequence of its characters spell the word hackerrank. For example, if string it does contain hackerrank, but does not. In the second case, the second r is…
Sami's spaceship crashed on Mars! She sends a series of SOS messages to Earth for help. Letters in some of the SOS messages are altered by cosmic radiation during transmission. Given the signal received by Earth as a…
Alice wrote a sequence of words in CamelCase as a string of letters, , having the following properties: It is a concatenation of one or more words consisting of English letters. All letters in the first word are…
You are given a square map as a matrix of integer strings. Each cell of the map has a value denoting its depth. We will call a cell of the map a cavity if and only if this cell is not on the border of the map and each…
You are the benevolent ruler of Rankhacker Castle, and today you're distributing bread. Your subjects are in a line, and some of them already have some loaves. Times are hard and your castle's food stocks are dwindling…
Lisa just got a new math workbook. A workbook contains exercise problems, grouped into chapters. Lisa believes a problem to be special if its index (within a chapter) is the same as the page number where it's located…
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…
Little Bobby loves chocolate. He frequently goes to his favorite store, Penny Auntie, to buy them. They are having a promotion at Penny Auntie. If Bobby saves enough wrappers, he can turn them in for a free chocolate…
Given a sequence of integers , a triplet is beautiful if: Given an increasing sequence of integers and the value of , count the number of beautiful triplets in the sequence. For example, the sequence and . There are…
A modified Kaprekar number is a positive whole number with a special property. If you square it, then split the number into two integers and sum those integers, you have the same value you started with. Consider a…
Taum is planning to celebrate the birthday of his friend, Diksha. There are two types of gifts that Diksha wants from Taum: one is black and the other is white. To make her happy, Taum has to buy black gifts and white…
Karl has an array of integers. He wants to reduce the array until all remaining elements are equal. Determine the minimum number of elements to delete to reach his goal. For example, if his array is , we see that he can…
Watson likes to challenge Sherlock's math ability. He will provide a starting and ending value describing a range of integers. Sherlock must determine the number of square integers within that range, inclusive of the…
Aerith is playing a cloud hopping game. In this game, there are sequentially numbered clouds that can be thunderheads or cumulus clouds. Her character must jump from cloud to cloud until it reaches the start again. To…
