Discussion on Circular Array Rotation Challenge

Sort 2305 Discussions, By:

5 years ago+ 0 comments

Easy and fast as hell --> O(n) time and O(1) Space........

public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    int N = in.nextInt();
    int K = in.nextInt();
    int Q = in.nextInt();
    int rot = K % N;
    int[] arr = new int[N];
    for (int i = 0; i < N; i++)
        arr[i] = in.nextInt();
    for (int i = 0; i < Q; i++) {
        int idx = in.nextInt();
        if (idx - rot >= 0)
            System.out.println(arr[idx - rot]);
        else
            System.out.println(arr[idx - rot + arr.length]);
		}
	}

Thanks for the votes guys. I never thought my solution would be on the top of the discussion forums. Anyways here is the mod based solution which many people found useful. Godspeed!

public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    int n = in.nextInt();
    int k = in.nextInt();
    int q = in.nextInt();
    int[] a = new int[n];
    for(int a_i=0; a_i < n; a_i++){
        a[a_i] = in.nextInt();
    }
    for(int a0 = 0; a0 < q; a0++){
        int m = in.nextInt();
        System.out.println(a[(n - (k % n)+ m) % n]);
    }               
}

5 years ago+ 0 comments

Here is another Java solution

public static void main(String[] args) {

    Scanner in = new Scanner(System.in);
    int n, k ,q;
    n = in.nextInt();
    k = in.nextInt();
    q = in.nextInt();

    int[] arr = new int[n];
    for(int i=0; i<n; i++) {
        arr[(i+k)%n] = in.nextInt();
    }
    for(int i=0; i<q; i++) {
        System.out.println(arr[in.nextInt()]);
    }
}

5 years ago+ 0 comments

Long live Python and its negative indexes ;)

4 years ago+ 0 comments

We don't need to actually rotate the array. We can just use basic math to pull the entry from the original array:

        int shift = n - (k % n);
        int index = (shift + m ) % n;

2 years ago+ 0 comments

static int[] circularArrayRotation(int[] a, int k, int[] queries) {

            int arr[] = new int[a.length];
						
            for(int i=0 ; i<a.length ; i++)
                arr[(i+k)%a.length] = a[i];
								
            for(int i=0 ; i<queries.length ; i++)
                queries[i] = arr[queries[i]];
								
            return queries;    

    }

Load more conversations