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 letters that match, and he deletes them. For instance, the string aab could be shortened to b in one operation.

Steve’s task is to delete as many characters as possible using this method and print the resulting string. If the final string is empty, print Empty String

About Tutorial Challenges

Many of the challenges on HackerRank are difficult and assume that you already know the relevant algorithms. These tutorial challenges are different. They break down algorithmic concepts into smaller challenges so that you can learn the algorithm by solving them. They are intended for those who already know some programming, however. You could be a student majoring in computer science, a self-taught programmer, or an experienced developer who wants an active algorithms review. Here’s a great place to learn by doing!

The first series of challenges covers sorting. They are listed below:

Your local library needs your help! Given the expected and actual return dates for a library book, create a program that calculates the fine (if any). The fee structure is as follows:

1. If the book is returned on or before the expected return date, no fine will be charged (i.e.: fine = 0).
2. If the book is returned after the expected return day but still within the same calendar month and year as the expected return date, fine = 15 Hackos X (the number of days late).
3. If the book is returned after the expected return month but still within the same calendar year as the expected return date, the fine = 500 Hackos X (the number of days late).
4. If the book is returned after the calendar year in which it was expected, there is a fixed fine of 10,000 Hackos.

Charges are based only on the least precise measure of lateness. For example, whether a book is due January 1, 2017 or December 31, 2017, if it is returned January 1, 2018, that is a year late and the fine would be .

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 lowercase.
• For each of the subsequent words, the first letter is uppercase and rest of the letters are lowercase.

Given s, print the number of words in s on a new line.

For example, s = oneTwoThree. There are 3 words in the string.

Overview

React는 사용자 인터페이스를 구축하기 위한 선언적이고 효율적이며 유연한 JavaScript 라이브러리입니다.

“컴포넌트”라고 불리는 작고 고립된 코드의 파편을 이용하여 복잡한 UI를 구성하도록 돕습니다.

Given a sequence of n integers, p(1),p(2),…,p(n) where each element is distinct and satisfies 1 <= p(x) <= n. For each x where 1 <= x <= n, find any integer y such that p(p(y)) = x and print the value of y on a new line.

For example, assume the sequence p = [5, 2, 1, 3, 4]. Each value of x between 1 and 5, the length of the sequence, is analyzed as follows:

1. , so p[p[4]] = 1
2. , so p[p[2]] = 2
3. , so p[p[5]] = 3
4. , so p[p[1]] = 4
5. , so p[p[3]] = 5

The values for y are [4,2,5,1,3].

What is a Browser?

웹 브라우저는 인터넷 망에서 웹(www)서비스를 이용할 수 있게 하여 정보를 검색하고 정보를 볼 수 있게 해주는 응용프로그램 입니다.

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 endpoints.

Note: A square integer is an integer which is the square of an integer, e.g. 1,4,9,16.25.

For example, the range is a = 24 and b = 49, inclusive. There are three square integers in the range: 25, 36 and 49.

The Utopian Tree goes through 2 cycles of growth every year. Each spring, it doubles in height. Each summer, its height increases by 1 meter.

Laura plants a Utopian Tree sapling with a height of 1 meter at the onset of spring. How tall will her tree be after n growth cycles?

For example, if the number of growth cycles is n = 5, the calculations are as follows:

1
2
3
4
5
6
7

Period  Height
0          1
1          2
2          3
3          6
4          7
5          14

When you select a contiguous block of text in a PDF viewer, the selection is highlighted with a blue rectangle. In this PDF viewer, each word is highlighted independently. For example:

In this challenge, you will be given a list of letter heights in the alphabet and a string. Using the letter heights given, determine the area of the rectangle highlight in mm² assuming all letters are 1mm wide.

For example, the highlighted word = torn. Assume the heights of the letters are t = 2, o = 1, r = 1 and n = 1. The tallest letter is 2 high and there are 4 letters. The hightlighted area will be 2 * 4 = 8mm² so the answer is 8.