Spiral Rectangle Hybrid (Numbers + Alphabets)

This program prints a rectangular spiral alternating numbers and alphabets.

Problem Statement

Write a Java program that prints a 5x7 rectangle where spiral order alternates numbers and alphabets.

Source Code

1 public class SpiralRectangleNumbersAlphabets {
2 public static void main(String[] args) {
3 int rows=5, cols=7, num=1;
4 String[][] arr=new String[rows][cols];
5 int top=0, left=0, bottom=rows-1, right=cols-1;
6 char ch='A'; boolean number=true;
7 while(top<=bottom && left<=right) {
8 for(int i=left; i<=right; i++) arr[top][i]=number?String.valueOf(num++):String.valueOf(ch++);
9 number=!number; top++;
10 for(int i=top; i<=bottom; i++) arr[i][right]=number?String.valueOf(num++):String.valueOf(ch++);
11 number=!number; right--;
12 for(int i=right; i>=left; i--) arr[bottom][i]=number?String.valueOf(num++):String.valueOf(ch++);
13 number=!number; bottom--;
14 for(int i=bottom; i>=top; i--) arr[i][left]=number?String.valueOf(num++):String.valueOf(ch++);
15 number=!number; left++;
16 if(ch>'Z') ch='A';
17 }
18 for(int i=0; i<rows; i++) {
19 for(int j=0; j<cols; j++) System.out.print(arr[i][j] + "\t");
20 System.out.println();
21 }
22 }
23 }

Program Output

1   A   2   B   3   C   4   
N   O   P   Q   R   S   5   
M   Z   A   B   C   T   6   
L   Y   X   W   D   U   7   
K   J   I   H   G   F   E   

Explanation

A boolean toggle alternates each boundary loop between filling with sequential numbers and sequential alphabets, and the alphabet character resets after 'Z', producing a rectangular spiral hybrid of numbers and letters.

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