[LeetCode][Kotlin] 189. Rotate Array

189. Rotate Array

Given an integer array nums, rotate the array to the right by k steps, where k is non-negative.

정수 배열 nums가 주어지면, 배열을 k 단계만큼 오른쪽으로 회전합니다. 여기서 k는 음수가 아닙니다.

 

Example 1:

Input: nums = [1,2,3,4,5,6,7], k = 3

Output: [5,6,7,1,2,3,4]

Explanation:

rotate 1 steps to the right: [7,1,2,3,4,5,6]

rotate 2 steps to the right: [6,7,1,2,3,4,5]

rotate 3 steps to the right: [5,6,7,1,2,3,4]

 

Example 2:

Input: nums = [-1,-100,3,99], k = 2

Output: [3,99,-1,-100]

 

Explanation: 

rotate 1 steps to the right: [99,-1,-100,3]

rotate 2 steps to the right: [3,99,-1,-100]

 

Constraints:

• 1 <= nums.length <= 10^5
• -2^31 <= nums[i] <= 2^31 - 1
• 0 <= k <= 10^5

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코드

class Solution {
    fun rotate(nums: IntArray, k: Int): Unit {
        var k = k % nums.size

        var l = 0 
        var r = nums.lastIndex
        while (l < r) {
            nums[l] = nums[r].also { nums[r] = nums[l] }
            l++
            r--
        }

        l = 0
        r = k - 1
        while (l < r) {
            nums[l] = nums[r].also { nums[r] = nums[l] }
            l++
            r--
        }

        l = k
        r = nums.lastIndex
        while (l < r) {
            nums[l] = nums[r].also { nums[r] = nums[l] }
            l++
            r--
        }
    }
}