artemkorsakov's solution

to Secret Handshake in the Java Track

Published at Feb 28 2019 · 0 comments
Instructions
Test suite
Solution

There are 10 types of people in the world: Those who understand binary, and those who don't.

You and your fellow cohort of those in the "know" when it comes to binary decide to come up with a secret "handshake".

``````1 = wink
1000 = jump

10000 = Reverse the order of the operations in the secret handshake.
``````

Given a decimal number, convert it to the appropriate sequence of events for a secret handshake.

Here's a couple of examples:

Given the input 3, the function would return the array ["wink", "double blink"] because 3 is 11 in binary.

Given the input 19, the function would return the array ["double blink", "wink"] because 19 is 10011 in binary. Notice that the addition of 16 (10000 in binary) has caused the array to be reversed.

Running the tests

You can run all the tests for an exercise by entering

``````\$ gradle test
``````

Source

Bert, in Mary Poppins http://www.imdb.com/title/tt0058331/quotes/qt0437047

Submitting Incomplete Solutions

It's possible to submit an incomplete solution so you can see how others have completed the exercise.

HandshakeCalculatorTest.java

``````import org.junit.Ignore;
import org.junit.Before;
import org.junit.Test;

import static java.util.Arrays.asList;
import static java.util.Collections.emptyList;
import static java.util.Collections.singletonList;
import static org.junit.Assert.assertEquals;

public class HandshakeCalculatorTest {

private HandshakeCalculator handshakeCalculator;

@Before
public void setUp() {
handshakeCalculator = new HandshakeCalculator();
}

@Test
public void testThatInput1YieldsAWink() {
assertEquals(
singletonList(Signal.WINK),
handshakeCalculator.calculateHandshake(1));
}

@Ignore("Remove to run test")
@Test
assertEquals(
handshakeCalculator.calculateHandshake(2));
}

@Ignore("Remove to run test")
@Test
public void testThatInput4YieldsACloseYourEyes() {
assertEquals(
singletonList(Signal.CLOSE_YOUR_EYES),
handshakeCalculator.calculateHandshake(4));
}

@Ignore("Remove to run test")
@Test
public void testThatInput8YieldsAJump() {
assertEquals(
singletonList(Signal.JUMP),
handshakeCalculator.calculateHandshake(8));
}

@Ignore("Remove to run test")
@Test
public void testAnInputThatYieldsTwoActions() {
assertEquals(
handshakeCalculator.calculateHandshake(3));
}

@Ignore("Remove to run test")
@Test
public void testAnInputThatYieldsTwoReversedActions() {
assertEquals(
handshakeCalculator.calculateHandshake(19));
}

@Ignore("Remove to run test")
@Test
public void testReversingASingleActionYieldsTheSameAction() {
assertEquals(
singletonList(Signal.JUMP),
handshakeCalculator.calculateHandshake(24));
}

@Ignore("Remove to run test")
@Test
public void testReversingNoActionsYieldsNoActions() {
assertEquals(
emptyList(),
handshakeCalculator.calculateHandshake(16));
}

@Ignore("Remove to run test")
@Test
public void testInputThatYieldsAllActions() {
assertEquals(
handshakeCalculator.calculateHandshake(15));
}

@Ignore("Remove to run test")
@Test
public void testInputThatYieldsAllActionsReversed() {
assertEquals(
handshakeCalculator.calculateHandshake(31));
}

@Ignore("Remove to run test")
@Test
public void testThatInput0YieldsNoActions() {
assertEquals(
emptyList(),
handshakeCalculator.calculateHandshake(0));
}

}``````
``````import java.util.ArrayList;
import java.util.Collections;
import java.util.List;

class HandshakeCalculator {

List<Signal> calculateHandshake(int number) {
String binary = Integer.toBinaryString(number);
List<Signal> result = new ArrayList<>();
for (int i = 1; i <= Math.min(binary.length(), 4); i++) {
if (binary.charAt(binary.length() - i) == '1') {
}
}
if (binary.length() > 4) {
Collections.reverse(result);
}
return result;
}
}``````