Question

I have a matrix with n columns, n rows and every element is initialized with 0.

I want to select the largest circle in that matrix, and set the values to 1.

000010000
000111000
000111000
001111100
011111110     The drawing isnt't very artistic (or correct)...  
001111100        matrix: 9*9
000111000        largest circle
000111000
000010000

Can you help me with the java algorithm ?

Language: Java

Thank you,
Horatiu

Answer 1

Here’s a naive algorithm. It fills in each point to a 0 or 1 depending upon whether it lies inside or outside the circle.

public static void main(String[] args)
{
    int[][] matrix = new int[9][];
    double midPoint = (matrix.length-1)/2.0;
    for (int col = 0; col < matrix.length; col++)
    {
        int[] row = new int[matrix.length];
        double yy = col-midPoint;
        for (int x=0; x<row.length; x++)
        {
           double xx = x-midPoint;
           if (Math.sqrt(xx*xx+yy*yy)<=midPoint)
             row[x] = 1;
           System.out.print(row[x]);
        }
        matrix[col] = row;
        System.out.println();
    }

}