Coding Dojo 2012-07-11

output.txt

+

 + 
+ +
 + 

  +  
 + + 
+   +
 + + 
  +  

   +   
  + +  
 +   + 
+     +
 +   + 
  + +  
   +   

star.hs

star :: Int -> String
star n = unlines [[if x + y == n + 1 then '+' else ' ' | x <- idx] | y <- idx]
    where idx = [1..n] ++ reverse [1..n - 1]

main :: IO ()
main = do
    putStrLn $ star 1
    putStrLn $ star 2
    putStrLn $ star 3
    putStrLn $ star 4

star.java

import java.util.ArrayList;
import java.util.List;

public class Star {
    private static List<Integer> makeIndices(int size) {
        List<Integer> indices = new ArrayList<Integer>(size * 2 - 1);
        for (int i = 1; i <= size; i++) {
            indices.add(i);
        }
        for (int i = size - 1; i >= 1; i--) {
            indices.add(i);
        }
        return indices;
    }

    private static String star(int size) {
        StringBuilder builder = new StringBuilder((size + 1) * size);
        List<Integer> indices = makeIndices(size);
        for (int x : indices) {
            for (int y : indices) {
                builder.append((x + y == size + 1) ? '+' : ' ');
            }
            builder.append('\n');
        }
        return builder.toString();
    }


    public static void main(String[] args) {
        System.out.println(star(1));
        System.out.println(star(2));
        System.out.println(star(3));
        System.out.println(star(4));
    }
}