[코딜리티] Lesson 2 - Arrays : Cycle Rotation

Lesson 2 - Arrays : Cycle Rotation

📌 문제

An array A consisting of N integers is given. Rotation of the array means that each element is shifted right by one index, and the last element of the array is moved to the first place. For example, the rotation of array A = [3, 8, 9, 7, 6] is [6, 3, 8, 9, 7] (elements are shifted right by one index and 6 is moved to the first place).

The goal is to rotate array A K times; that is, each element of A will be shifted to the right K times.

Write a function:

class Solution { public int[] solution(int[] A, int K); }

that, given an array A consisting of N integers and an integer K, returns the array A rotated K times.

For example, given

A = [3, 8, 9, 7, 6]
K = 3

the function should return [9, 7, 6, 3, 8]. Three rotations were made:

[3, 8, 9, 7, 6] -> [6, 3, 8, 9, 7]
[6, 3, 8, 9, 7] -> [7, 6, 3, 8, 9]
[7, 6, 3, 8, 9] -> [9, 7, 6, 3, 8]

For another example, given

A = [0, 0, 0]
K = 1

the function should return [0, 0, 0]

Given

A = [1, 2, 3, 4]
K = 4

the function should return [1, 2, 3, 4]

Assume that:

• N and K are integers within the range [0..100];
• each element of array A is an integer within the range [−1,000..1,000].

In your solution, focus on correctness. The performance of your solution will not be the focus of the assessment.

📝 풀이

로테이션 시 맨 마지막 숫자가 맨 첫번째 자리로 오는 순환식 구조이기 때문에 현재 자리에서 로테이션 한 횟수만큼 더하고 원 배열의 길이만큼으로 나눈 나머지를 구하면 옮긴 자리의 idx를 구할 수 있다.

💻 구현

static class Solution {
    public int[] solution(int[] A, int K) {
        int[] answer = new int[A.length];
        for(int i = 0; i < A.length; i++){
            answer[(i + K) % A.length] = A[i];
        }

        return answer;
    }
}