3. Rotate Array

Arpit Khurana
1 min readOct 2, 2020

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

Follow up:

  • Try to come up as many solutions as you can, there are at least 3 different ways to solve this problem.
  • Could you do it in-place with O(1) extra space?

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 <= 2 * 10^4
  • It’s guaranteed that nums[i] fits in a 32 bit-signed integer.
  • k >= 0

My solution

class Solution {
public void rotate(int[] a, int k) {

int len = a.length;
int temp = -1;

while(k > 0){
temp = a[len-1];
for(int i=len-1;i>0;i — ) {
a[i] = a[i-1];
}
a[0] = temp;
k — ;
}

}
}

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Arpit Khurana
Arpit Khurana

Written by Arpit Khurana

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