(LeetCode) Rotate Array

Rotate Array

  • 분류 : Array
  • 난이도 : Easy

Problem

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

Example 1

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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

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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 <= 2 * 10^4
  • -2^31 <= nums[i] <= 2^31 - 1
  • 0 <= k <= 10^5

Solution (Not supported in LeetCode)

Exapnder
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class Solution {
fun rotate(nums: IntArray, k: Int): Unit {
nums.reverse(nums.size - k, nums.size)
nums.reverse(0, nums.size - k)
nums.reverse()
}
}

Solution

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class Solution {
fun rotate(nums: IntArray, k: Int): Unit {
for (i in 0 until k) {
var index = nums.size - 1
var temp = nums[index]
for (j in index downTo 1) {
nums[j] = nums[j - 1]
}
nums[0] = temp
}
}
}

Point of Thinking

  • K를 기준으로 reverse를 3번하면 된다.
    • LeetCode에서는 IntArray.reverse()를 지원하지않는다..
  • 결국 2중 for loop로 풀었다.