Logic behind pattern...

Suppose you want to draw Following pattern in java...But the que. is how..?

let's view logic behind this pattern...

       *
     * * *
   * * * * *
* * * * * * *

consider j = *, i=row

so when ,

i=1, j=1

i=2, j=3

i=3, j=5... and so on...

so from above we get j= (2*i) - 1

now let do same thing for white space which are used before the *... 

let take j=white space and i=row

so when...

i=1, j=3

i=2, j=2

i=3, j=1...nd so on...

so we got... j = n - i

so now lets write program using above equation...

class pattern

{

public static void main(String [] args)

{

int i,j,n=5;

System.out.println("hi");

for(i=1;i<=5;i++)

{

for(j=i-1;j>0;j--)

{

System.out.print(" ");

}

for(j=(n-i)*2+1;j>0;j--)

{

System.out.print("*");

}

System.out.println();

}

}

}

output :-

       *
     * * *
   * * * * *
* * * * * * *