Spiral Trapezoid of Numbers
This program prints a trapezoid filled with numbers in spiral order.
Problem Statement
Write a Java program that prints a trapezoid of 5 rows filled with numbers in spiral order.
Source Code
| 1 | public class SpiralTrapezoidNumbers { |
| 2 | public static void main(String[] args) { |
| 3 | int rows=5, cols=9; |
| 4 | int[][] arr=new int[rows][cols]; |
| 5 | int top=0, left=0, bottom=rows-1, right=cols-1, num=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<rows;i++){ |
| 17 | for(int j=0;j<cols;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 6 7 8 9 18 10 17 24 25 26 27 11 16 23 22 21 12 15 14 13
Explanation
The standard rectangular spiral fill logic is applied to a wider 5x9 matrix, and since not every cell gets filled by the spiral in this shape, unfilled cells remain zero and are printed as blanks, giving a trapezoid-like appearance.