LeetCode 189.

Intuition

keep a subarray of right side of array and replace right side of it by left side. After that, replace the other side.

Approach

• create a subarray which size is equal to k to keep the right side of array
• replace right side by left side first
• then replace left side by right side

Complexity

• Time complexity: O(n)

• Space complexity: O(k)

Code

class Solution {
    public void rotate(int[] nums, int k) {
        k = k % nums.length;
        int[] tmp = new int[k];
        for (int i=nums.length-k; i<nums.length; i++) {
            tmp[i + k - nums.length] = nums[i];
        }

        for (int i=nums.length-k-1; i>=0; i--) {
            nums[i + k] = nums[i];
        }
        for (int i=0; i<k; i++) {
            nums[i] = tmp[i];
        }
    }
}

Check out the description of this problem at LC 189.