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189. Rotate Array

배열을 k번 오른쪽으로 회전시키는 문제를 여러가지 솔루션으로 해결하기

Oct 1, 2025 — hash

문제 설명

1st Solution: Time O(n * k)

/**
 Do not return anything, modify nums in-place instead.
 */
function rotate(nums: number[], k: number): void {
    while (k > 0) {
        nums.unshift(nums.pop());
        k -= 1;
    }
};

2nd Solution : Time O(n) Space O(n)

/**
 Do not return anything, modify nums in-place instead.
 */
function rotate(nums: number[], k: number): void {
    const N = nums.length;


    const rotated = Array(N).fill(0);


    for (let i = 0; i < N; i += 1) {
        rotated[(i + k) % N] = nums[i];
    }


    for (let i = 0; i < N; i += 1) {
        nums[i] = rotated[i];
    }
};

3rd Solution : Time O(n) Space O(n)

/**
 Do not return anything, modify nums in-place instead.
 */
function rotate(nums: number[], k: number): void {
    const N = nums.length;
    const M = k % N;


    const temp = [
        ...nums.slice(-M),
        ...nums.slice(0, -M)
    ]


    for (let i = 0; i < N; i += 1) {
        nums[i] = temp[i];
    }
};

4th Solution : Time O(n) Space O(1)

/**
 Do not return anything, modify nums in-place instead.
 */
function rotate(nums: number[], k: number): void {
    const N = nums.length;
    k = k % N;


    const reverse = (array, left, right) => {
        while (left < right) {
            [ array[left], array[right] ] = [ array[right], array[left] ];
            left += 1;
            right -= 1;
        }
    }


    reverse(nums, 0, N - 1);
    reverse(nums, 0, k - 1);
    reverse(nums, k, N - 1);
};