package ch.claude_martin.playground;

import java.io.FilterOutputStream;
import java.io.OutputStream;
import java.io.PrintStream;
import java.lang.reflect.Field;

public final class SomeClass {
	final static int[] sizeTable = { 9, 99, 999, 9999, 99999, 999999, 9999999, 99999999, 999999999, Integer.MAX_VALUE };

	static int stringSize(int x) {
		for (int i = 0;; i++)
			if (x <= sizeTable[i])
				return i + 1;
	}

	static boolean increment(byte[] buf, int off) {
		if (buf[off] == 0) {
			buf[off] = '1';
			return true;
		}
		if (buf[off] == '9') {
			buf[off] = '0';
			return increment(buf, off - 1);
		}
		buf[off]++;
		return false;
	}

	public static void main(String... args) throws Throwable {
		final long start = System.nanoTime();
		final int n = 10000000;
		// IntStream.rangeClosed(0, lastNumber).forEach(System.out::println);
		final int size = stringSize(n);
		byte[] buf = new byte[size + 1];
		buf[size-1] = '0';
		buf[size] = '\n';
		final Field field = FilterOutputStream.class.getDeclaredField("out");
		field.setAccessible(true);
		OutputStream out = (OutputStream) field.get(System.out);
		int off = size - 1;
		final int last = size - 1; // least significant byte

		for (int i = 0; i < n; i++) {
			if (increment(buf, last))
				off--;
			out.write(buf, off, size - off+1 );
		}
		final long end = System.nanoTime();
		System.out.println("====");
		System.out.println(end - start);
	}
}