Rotate String – HackerRank Solution

In this post, we will solve Rotate String HackerRank Solution. This problem (Rotate String) is a part of HackerRank Functional Programming series.

Task

Scturtle likes strings very much. He is getting bored today, because he has already completed this week’s task and doesn’t have anything else to do. So he starts left-rotating a string. If the length of the string is n, then he will rotate it n times and note down the result of each rotation on a paper.

For a string S = s₁ s₂ . . . s_n, n rotations are possible. Let’s represent these rotations by r₁, r₂ . . . r_n. Rotating it once will result in string r₁ = s₂s₃ . . . s_ns₁, rotating it again will result in string r₂ = s₃s₄ . . . s_ns₁s₂ and so on. Formally, i^th rotation will be equal to r_i = s_i+1 . . . s_n-1 s_n s₁ . . . s_i. Note that r_n = S.

Your task is to display all n rotations of string S.

For example, if S = abc then it has 3 rotations. They are r₁ = bca, r₂ = cab and r₃ = abc.

Input Format

The first line contains an integer, T, which represents the number of test cases to follow. Then follows T lines, which represent a test case each.
Each test case contains a string, S, which consists of lower case latin characters (‘a‘ – ‘z‘) only.

Output Format

For each test case, print all the rotations, r₁ r₂ . . . r_n, separated by a space.

Constraints

• 1 <= T <= 10
• 1 <= n <= 10²
• S will consist of lower case latin character, [‘a‘ . . . ‘z‘] only.

Sample Input

5
abc
abcde
abab
aaa
z

Sample Output

bca cab abc
bcdea cdeab deabc eabcd abcde
baba abab baba abab
aaa aaa aaa
z

Explanation

Test case #1: This case is mentioned in the problem statment.
Test case #2: Rotations of abcde are: bcdea -> cdeab -> deabc -> eabcd -> abcde.
Test case #3: Rotations of abab are: baba -> abab -> baba -> abab.
Test case #4: All three rotations will result into same string.
Test case #5: Only one rotation is possible, and that will result into original string.

Solution – Rotate String – HackerRank Solution

Scala

import java.util.Scanner

object Solution {

  def main(args: Array[String]): Unit = {
    val sc = new Scanner(System.in)

    val t = sc.nextInt
    sc.nextLine

    (0 until t).foreach(_ => {
      val s = sc.nextLine

      case class Acc(s: String, answer: List[String])
      println((0 until s.length).foldLeft(Acc(s, Nil))((acc, _) => {
        val nextV = acc.s.tail + acc.s.head
        Acc(nextV, nextV :: acc.answer)
      }).answer.reverse.mkString(" "))
    })
  }
}

Note: This problem (Rotate String) is generated by HackerRank but the solution is provided by CodingBroz. This tutorial is only for Educational and Learning purpose.