2d-array rotation.java

import java.io.*;
import java.util.*;

public class Main {

    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int m = sc.nextInt();
        int mat[][] = new int[n][m];
        for (int i = 0; i < mat.length; i++) {
            for (int j = 0; j < mat[0].length; j++) {
                mat[i][j] = sc.nextInt();
            }
        }
        int s = sc.nextInt();
        int r = sc.nextInt();
        shellRotate(mat, s, r);
        display(mat);

    }
    public static void shellRotate(int mat[][], int s, int r) {
        int arr[] = fill1d(mat, s);
        rotate(arr, r);
        fill2d(mat, s, arr);
    }
    public static int[] fill1d(int mat[][], int s) {
        int rmin = s - 1, cmin = s - 1, rmax = mat.length - s, cmax = mat[0].length - s;
        int n = 2 * (rmax - rmin + cmax - cmin);
        int arr[] = new int[n];
        int idx = 0;
        //left wall
        for (int i = rmin; i <= rmax; i++) {
            arr[idx] = mat[i][cmin];
            idx++;
        }
        cmin++;
        //bottom wall
        for (int j = cmin; j <= cmax; j++) {
            arr[idx] = mat[rmax][j];
            idx++;
        }
        rmax--;
        //right wall
        for (int i = rmax; i >= rmin; i--) {
            arr[idx] = mat[i][cmax];
            idx++;
        }
        cmax--;
        //top wall
        for (int j = cmax; j >= cmin; j--) {
            arr[idx] = mat[rmin][j];
            idx++;
        }
        return arr;
    }
    public static void fill2d(int mat[][], int s, int arr[]) {
        int rmin = s - 1, cmin = s - 1, rmax = mat.length - s, cmax = mat[0].length - s;

        int idx = 0;
        //left wall
        for (int i = rmin; i <= rmax; i++) {
            mat[i][cmin] = arr[idx];
              
            idx++;
        }
        cmin++;
        //bottom wall
        for (int j = cmin; j <= cmax; j++) {
             mat[rmax][j] = arr[idx];
            idx++;
        }
        rmax--;
        //right wall
        for (int i = rmax; i >= rmin; i--) {
             mat[i][cmax] = arr[idx];
            idx++;
        }
        cmax--;
        //top wall
        for (int j = cmax; j >= cmin; j--) {
           mat[rmin][j] = arr[idx];
            idx++;
        }

    }
    public static void rotate(int arr[], int r) {
        r = r % arr.length;
        if (r < 0) {
            r = r + arr.length;
        }
        reverse(arr, arr.length - r, arr.length - 1);
        reverse(arr, 0, arr.length - r - 1);

        reverse(arr, 0, arr.length - 1);

    }
    public static void reverse(int arr[], int si, int ei) {
        while (si < ei) {
            int temp = arr[si];
            arr[si] = arr[ei];
            arr[ei] = temp;
            si++;
            ei--;
        }
    }
    public static void display(int[][] arr) {
        for (int i = 0; i < arr.length; i++) {
            for (int j = 0; j < arr[0].length; j++) {
                System.out.print(arr[i][j] + " ");
            }
            System.out.println();
        }
    }

}