import java.util.Random;

public class Main {

	static interface StripAlg {
		String strip(String old);
		String name();
	}

	private final static StripAlg strip1 = new StripAlg() {
		@Override
		public String strip(final String old) {
			final int length = old.length();
			final char[] oldChars = new char[length];
			old.getChars(0, length, oldChars, 0);
			int newLen = 0;
			for(int j = 0; j < length; j++) {
				final char ch = oldChars[j];
				if (ch >= ' ') {
					oldChars[newLen] = ch;
					newLen++;
				}
			}
			return new String(oldChars, 0, newLen);
		}

		@Override
		public String name() {
			return "Alg1";
		}
	};

	private final static StripAlg strip2 = new StripAlg() {
		@Override
		public String strip(final String old) {
			final StringBuffer sb = new StringBuffer(old.length());
			for(int i = 0; i < old.length(); i++) {
				final char ch = old.charAt(i);
				if (ch >= ' ') {
					sb.append(ch);
				}
			}
			return sb.toString();
		}

		@Override
		public String name() {
			return "Alg2";
		}
	};

	private final static StripAlg strip3 = new StripAlg() {
		@Override
		public String strip(final String old) {
			final int length = old.length();
			final char[] oldChars = new char[length + 1];
			old.getChars(0, length, oldChars, 0);
			oldChars[length] = '\0';// avoiding explicit bound check in while
			int newLen = -1;
			while(oldChars[++newLen] >= ' ')
				;// find first non-printable,
			// if there are none it ends on the null char I appended
			for(int j = newLen; j < length; j++) {
				final char ch = oldChars[j];
				if (ch >= ' ') {
					oldChars[newLen] = ch;// the while avoids repeated
											// overwriting here when newLen==j
					newLen++;
				}
			}
			return new String(oldChars, 0, newLen);
		}

		@Override
		public String name() {
			return "Alg3";
		}
	};

	private static String getTestString(final int size, final int maxCharVal, final long seed) {
		final Random rand = new Random(seed);
		final StringBuffer sb = new StringBuffer(size);
		for(int i = 0; i < size; i++) {
			sb.append((char) rand.nextInt(maxCharVal));
		}
		return sb.toString();
	}

	private static double testAlg(final StripAlg alg, final String test, final int runs) {
		final long start = System.nanoTime();
		for(int i = 0; i < runs; i++) {
			alg.strip(test);
		}
		final long end = System.nanoTime();
		return (double)(end - start) / 1000000;
	}

	public static void main(final String[] args) {
		final long seed = 0xdeadcafe;
		final int size = 200;
		final int maxCharVal = 200; // 32/200 ~ percentage of non printables
		final String test = getTestString(size, maxCharVal, seed);
		final int nrRuns = 10000;

		final StripAlg algs[] = { strip1, strip2, strip3 };
		for(final StripAlg alg : algs) {
			getTime(alg, size, test, nrRuns);
		}

	}

	private static void getTime(final StripAlg alg, final int size, final String test,
			final int nrRuns) {
		double minRun = Double.MAX_VALUE;
		for(int i = 0; i < 1000; i++) {
			minRun = Math.min(minRun, testAlg(alg, test, nrRuns));
		}
		System.out.printf("%s takes %.2fms per %d elements (%.2fops/s)%n", alg.name(), minRun, nrRuns,
				(double) nrRuns / minRun * 1000);
	}

}