Question

Write a java method that creates a two dimensional char array after asking the user to input a String text and String key consisting of integers only, such that

int rows=(int)Math.ceil(text.length()/key.length()); // or int rows=(int)Math.ceil(text.length()/key.length()); ?

int columns= key.length();

int remainder= text.length() % key.length(); // such that the last row avoids taking an index beyond the string text by making columns - remainder

The method fills the 2d array with letters a String entered by the use (row by row). The method then shifts the columns of the array based on key.

After changing the columns, the method returns a String of all the characters in the 2d array but written column by column.

text = Sara;

key= 312

For example, the initial 2d array is

S	A	R
A

transformed into

R	S	A
	A

The final retuned string is RSAA

Answer 1

Code with comments

import java.util.Scanner;

class Temp {

    static void print(char[][] arr) { // print char array as grid

        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();

        }

    }

    static void fun() {

        Scanner sc = new Scanner(System.in);

        String text = sc.nextLine();// input text

        String key = sc.nextLine();// input key

        sc.close();

        int cols = key.length();

        int rows = text.length() / cols;

        int rem = text.length() % cols;

        char[][] arr = new char[rows + 1][cols];// extra row for remainder

        for (int i = 0; i < rows; i++) {// fill row by row

            for (int j = 0; j < cols; j++) {// fill col by col

                arr[i][j] = text.charAt(cols * i + j);

            }

        }

        int j = 0;

        for (; j < rem; j++)// fill remainder

            arr[rows][j] = text.charAt(cols * rows + j);

        for (; j < cols; j++)// fikl zeros

            arr[rows][j] = 0;

        print(arr);

        String res = "";

        for (int i = 0; i < key.length(); i++) {

            int c = key.charAt(i) - '1'; // get column

            for (j = 0; j <= rows; j++) { // all rows of that column

                res += (arr[j][c] != 0 ? arr[j][c] : "");

            }

        }

        System.out.println(res);

    }

    public static void main(String[] args) {

        fun();

    }

}