diamond.java

public class diamond{

     public static void main(String []args){
        int size=11;
        for (int i=0; i<size; i++){ //высота
            for (int j=0; j<size; j++){
                if (
                (i==0 && j==size/2) || //up
                (j==i+size/2 && i<size/2+1) ||
                (j==size/2-i) ||
                (i==size-1 && j==size/2) || //down
                (j==i-size/2) ||
                (j==size/2-i+size-1)
                ){
                    System.out.print("O");
                }
                else{
                    System.out.print(" ");
                }
            }
            System.out.println();
        }
     }
}