Spiral Pyramid of Numbers
This program prints a pyramid filled with numbers in spiral order.
Problem Statement
Write a Java program that prints a pyramid of numbers arranged in spiral order with 5 rows.
Source Code
| 1 | public class SpiralPyramidNumbers { |
| 2 | public static void main(String[] args) { |
| 3 | int n = 5, num=1; |
| 4 | int[][] arr = new int[n][2*n-1]; |
| 5 | int top=0, left=n-1, bottom=n-1, right=n-1+(n-1); |
| 6 | while(top<=bottom && left<=right) { |
| 7 | for(int i=left; i<=right; i++) arr[top][i]=num++; |
| 8 | top++; |
| 9 | for(int i=top; i<=bottom; i++) arr[i][right]=num++; |
| 10 | right--; |
| 11 | for(int i=right; i>=left; i--) arr[bottom][i]=num++; |
| 12 | bottom--; |
| 13 | for(int i=bottom; i>=top; i--) arr[i][left]=num++; |
| 14 | left++; |
| 15 | } |
| 16 | for(int i=0; i<n; i++) { |
| 17 | for(int j=0; j<2*n-1; j++) { |
| 18 | if(arr[i][j]!=0) System.out.print(arr[i][j] + " "); |
| 19 | else System.out.print(" "); |
| 20 | } |
| 21 | System.out.println(); |
| 22 | } |
| 23 | } |
| 24 | } |
Program Output
1 2 3 4 5 16 6 15 24 25 20 7 14 23 22 21 8 13 12 11 10 9
Explanation
A trapezoid-shaped matrix is used with boundaries starting from the middle, and the standard spiral fill logic runs on this matrix so that when printed, unused cells remain blank producing a pyramid outline filled with spiral numbers.