Arrays / Javascript 문제 풀이

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:

function solution(A, 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.

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풀이

array가 N으로 들어오고 Circle 값 K가 들어오면 그만큼 Circle 이동해서 출력

A = [3, 8, 9, 7, 6] K = 3 일 때

[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]

결과: [9, 7, 6, 3, 8]

 

//처음 코드, 시간 복잡도 최악

// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A, K) {
    // write your code in JavaScript (Node.js 8.9.4)
    let result = [];
    let checked = Array.from({length: A.length}, () => 0);
    let circled = K-1;
    let index =0;

    if(K === A.length)
    return A;
    while(checked[circled] === 0) {
        result[index] = A[circled];
        checked[circled] = 1;
        index++;
        if(circled >= A.length-1) {
            circled = 0;
        }else {
        circled++;
        }
    }

    return result;
}

// 2번째 코드, Array size 만큼 나누어서 나머지로 돌리기만하면 간단하게 끝난다.

// you can write to stdout for debugging purposes, e.g.
// console.log('this is a debug message');

function solution(A, K) {
    // write your code in JavaScript (Node.js 8.9.4)
    let arraySize = A.length;

    result = new Array(arraySize);

        for (let i = 0; i < arraySize; i++) {
            result[(i + K) % arraySize] = A[i];
        }
        return result;
}