Printing a pyramid pattern of digits #4

//This java program accepts a number of user
//which tells the program that how many lines
//of the pattern will be printed and then prints
//the pattern of the given number of lines.
/*Sample Input :4
Sample Output :
1
0 1
1 0 1
0 1 0 1 */

import java.util.*;
class pattern
{
public static void main()
{
    System.out.print("Enter the number of lines you want : ");
    Scanner sc=new Scanner(System.in);
    int n=sc.nextInt();
    int i,j,c=1,k=-1;
    int a=1,b=-1;
    for(i=1;i<=n;i++)
    {
        c=a;
        k=b;
        for(j=1;j<=i;j++)
        {
            System.out.print(c+" ");
            c=c+k;     
            k=k*(-1);  
        }
        System.out.println();
        a=a+b;     
        b=b*(-1);
    }
}
}
//Author : Mayank Rajoria