binarytrees.java

package test.java.performance;

/* The Great Computer Language Shootout
 http://shootout.alioth.debian.org/

 contributed by Jarkko Miettinen
 */

public class binarytrees {

    private final static int minDepth = 4;

    public static void main(String[] args) {
        int n = 0;
        if (args.length > 0)
            n = Integer.parseInt(args[0]);

        int maxDepth = (minDepth + 2 > n) ? minDepth + 2 : n;
        int stretchDepth = maxDepth + 1;

        int check = (TreeNode.bottomUpTree(0, stretchDepth)).itemCheck();
        System.out.println("stretch tree of depth " + stretchDepth + "\t check: " + check);

        TreeNode longLivedTree = TreeNode.bottomUpTree(0, maxDepth);

        for (int depth = minDepth; depth <= maxDepth; depth += 2) {
            int iterations = 1 << (maxDepth - depth + minDepth);
            check = 0;

            for (int i = 1; i <= iterations; i++) {
                check += (TreeNode.bottomUpTree(i, depth)).itemCheck();
                check += (TreeNode.bottomUpTree(-i, depth)).itemCheck();
            }
            System.out.println((iterations * 2) + "\t trees of depth " + depth + "\t check: " + check);
        }
        System.out.println("long lived tree of depth " + maxDepth + "\t check: " + longLivedTree.itemCheck());
    }

    private static class TreeNode {
        private TreeNode left, right;
        private int item;

        TreeNode(int item) {
            this.item = item;
        }

        private static TreeNode bottomUpTree(int item, int depth) {
            if (depth > 0) {
                return new TreeNode(bottomUpTree(2 * item - 1, depth - 1), bottomUpTree(2 * item, depth - 1), item);
            } else {
                return new TreeNode(item);
            }
        }

        TreeNode(TreeNode left, TreeNode right, int item) {
            this.left = left;
            this.right = right;
            this.item = item;
        }

        private int itemCheck() {
            // if necessary deallocate here
            if (left == null)
                return item;
            else
                return item + left.itemCheck() - right.itemCheck();
        }
    }
}