LeetCode 189: Rotate Array Solution

Master LeetCode problem 189 (Rotate Array), a medium challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.

189. Rotate Array

Medium

Array Math Two Pointers

Problem Explanation

Explanation

To rotate an array to the right by k steps, we can use the following approach:

Reverse the entire array.
Reverse the first k elements.
Reverse the remaining elements.

This approach allows us to achieve the rotation in-place with O(1) extra space.

Time complexity: O(n), where n is the number of elements in the array. Space complexity: O(1).

Solution Code

class Solution {
    public void rotate(int[] nums, int k) {
        k %= nums.length;
        
        reverse(nums, 0, nums.length - 1);
        reverse(nums, 0, k - 1);
        reverse(nums, k, nums.length - 1);
    }
    
    private void reverse(int[] nums, int start, int end) {
        while (start < end) {
            int temp = nums[start];
            nums[start] = nums[end];
            nums[end] = temp;
            start++;
            end--;
        }
    }
}

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