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özkan pakdil
özkan pakdil

Posted on • Originally published at ozkanpakdil.github.io on

Turning an array clockwise or counterclockwise

Turn an array clockwise therefore the last element comes to first and all hops to right.
And counterclockwise meaning last element comes to first and others hops to their left.


import java.io.IOException;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;

public class Solution {
    public static void main(String[] args) throws IOException {
        int[] arr = new int[]{1, 3, 5, 7, 9};
        int K = 3;
        turnTheArrayToRight(arr, K);
        System.out.println("-----------");
        turnTheArrayToLeft(arr, K);

        System.out.println("-----------");
        // no need to reinvent the wheel.
        List l = new ArrayList<>();
        Arrays.stream(arr).forEach(i->l.add(i));
        Collections.rotate(l, K); // rotate right
        System.out.println(Arrays.toString(l.toArray()));
        Collections.rotate(l, -1 * K); // rotate left
        System.out.println(Arrays.toString(l.toArray()));
    }

    private static int[] turnTheArrayToRight(int[] nums, int k) {
        for (int j = 0; j < k; j++) {
            for (int i = nums.length - 1; 0 < i; i--) {
                int temp = nums[i - 1];
                nums[i - 1] = nums[i];
                nums[i] = temp;
            }
            System.out.println(Arrays.toString(nums));
        }
        return nums;
    }

    private static int[] turnTheArrayToLeft(int[] nums, int k) {
        for (int j = 0; j < k; j++) {
            for (int i = 0; i < nums.length - 1; i++) {
                int temp = nums[i];
                nums[i] = nums[i + 1];
                nums[i + 1] = temp;
            }
            System.out.println(Arrays.toString(nums));
        }
        return nums;
    }
}
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Output

[9, 1, 3, 5, 7]
[7, 9, 1, 3, 5]
[5, 7, 9, 1, 3]
-----------
[7, 9, 1, 3, 5]
[9, 1, 3, 5, 7]
[1, 3, 5, 7, 9]
-----------
[5, 7, 9, 1, 3]
[1, 3, 5, 7, 9]
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