Added exercise crypto-square

config.json

@@ -25,7 +25,8 @@
     "allergies",
     "strain",
     "atbash-cipher",
-    "accumulate"
+    "accumulate",
+    "crypto-square"
   ],
   "deprecated": [
   ],

crypto-square/build.gradle

@@ -0,0 +1,11 @@
+apply plugin: "java"
+apply plugin: "eclipse"
+apply plugin: "idea"
+
+repositories {
+  mavenCentral()
+}
+
+dependencies {
+  testCompile "junit:junit:4.10"
+}

crypto-square/example.java

@@ -0,0 +1,72 @@
+import java.util.ArrayList;
+import java.util.List;
+
+public class Crypto {
+
+    private String normalizedPlaintext;
+    private int squareSize;
+
+    public Crypto(String text) {
+        this.normalizedPlaintext = normalizeText(text);
+        this.squareSize = calculateSquareSize(normalizedPlaintext);
+    }
+
+    public String getNormalizedPlaintext() {
+        return normalizedPlaintext;
+    }
+
+    public int getSquareSize() {
+        return squareSize;
+    }
+
+    private static String normalizeText(String text) {
+        return text.toLowerCase().codePoints()
+                .filter(x -> Character.isLetterOrDigit(x))
+                .collect(StringBuilder::new, StringBuilder::appendCodePoint, StringBuilder::append)
+                .toString();
+    }
+
+    private static int calculateSquareSize(String text) {
+        return (int) Math.ceil(Math.sqrt(text.length()));
+    }
+
+    public List<String> getPlaintextSegments() {
+        return getSegmentText(normalizedPlaintext, squareSize);
+    }
+
+    private static List<String> getSegmentText(String text, int squareSize) {
+        List<String> segments = new ArrayList<>();
+        int index = 0;
+
+        while (index < text.length()) {
+            if (index + squareSize < text.length()) {
+                segments.add(text.substring(index, index + squareSize));
+            } else {
+                segments.add(text.substring(index));
+            }
+            index += squareSize;
+        }
+
+        return segments;
+    }
+
+    public String getCipherText() {
+        StringBuilder cipherText = new StringBuilder(normalizedPlaintext.length());
+
+        for (int index = 0; index < squareSize; index++) {
+            for (String segment : getPlaintextSegments()) {
+                if (index < segment.length()) {
+                    cipherText.append(segment.charAt(index));
+                }
+            }
+        }
+
+        return cipherText.toString();
+    }
+
+    public String getNormalizedCipherText() {
+        String cipher = getCipherText();
+
+        return String.join(" ", getSegmentText(cipher, squareSize - 1));
+    }
+}

crypto-square/src/main/java/Crypto.java

@@ -0,0 +1,2 @@
+public class Crypto {
+}

crypto-square/src/test/java/CryptoSquareTest.java

@@ -0,0 +1,129 @@
+import org.junit.Test;
+
+import java.util.Arrays;
+import java.util.List;
+
+import static org.junit.Assert.assertEquals;
+
+public class CryptoSquareTest {
+
+    @Test
+    public void strangeCharactersAreStrippedDuringNormalization() {
+        Crypto crypto = new Crypto("s#$%^&plunk");
+        String expectedOutput = "splunk";
+
+        assertEquals(expectedOutput, crypto.getNormalizedPlaintext());
+    }
+
+    @Test
+    public void lettersAreLowerCasedDuringNormalization() {
+        Crypto crypto = new Crypto("WHOA HEY!");
+        String expectedOutput = "whoahey";
+
+        assertEquals(expectedOutput, crypto.getNormalizedPlaintext());
+    }
+
+    @Test
+    public void numbersAreKeptDuringNormalization() {
+        Crypto crypto = new Crypto("1, 2, 3, GO!");
+        String expectedOutput = "123go";
+
+        assertEquals(expectedOutput, crypto.getNormalizedPlaintext());
+    }
+
+    @Test
+    public void smallestSquareSizeIs2() {
+        Crypto crypto = new Crypto("1234");
+        int expectedOutput = 2;
+
+        assertEquals(expectedOutput, crypto.getSquareSize());
+    }
+
+    @Test
+    public void sizeOfTextWhoseLengthIsPerfectSquareIsItsSquareRoot() {
+        Crypto crypto = new Crypto("123456789");
+        int expectedOutput = 3;
+
+        assertEquals(expectedOutput, crypto.getSquareSize());
+    }
+
+    @Test
+    public void sizeOfTextWhoseLengthIsNoPerfectSquareIsNextBiggestSquareRoot() {
+        Crypto crypto = new Crypto("123456789abc");
+        int expectedOutput = 4;
+
+        assertEquals(expectedOutput, crypto.getSquareSize());
+    }
+
+    @Test
+    public void sizeIsDeterminedByNormalizedText() {
+        Crypto crypto = new Crypto("Oh hey, this is nuts!");
+        int expectedOutput = 4;
+
+        assertEquals(expectedOutput, crypto.getSquareSize());
+    }
+
+    @Test
+    public void segmentsAreSplitBySquareSize() {
+        Crypto crypto = new Crypto("Never vex thine heart with idle woes");
+        List<String> expectedOutput = Arrays.asList(new String[]{"neverv", "exthin", "eheart", "withid", "lewoes"});
+
+        assertEquals(expectedOutput, crypto.getPlaintextSegments());
+    }
+
+    @Test
+    public void segmentsAreSplitBySquareSizeUntilTextRunsOut() {
+        Crypto crypto = new Crypto("ZOMG! ZOMBIES!!!");
+        List<String> expectedOutput = Arrays.asList(new String[]{"zomg", "zomb", "ies"});
+
+        assertEquals(expectedOutput, crypto.getPlaintextSegments());
+    }
+
+    @Test
+    public void cipherTextCombinesTextByColumn() {
+        Crypto crypto = new Crypto("First, solve the problem. Then, write the code.");
+        String expectedOutput = "foeewhilpmrervrticseohtottbeedshlnte";
+
+        assertEquals(expectedOutput, crypto.getCipherText());
+    }
+
+    @Test
+    public void cipherTextSkipsCellsWithNoText() {
+        Crypto crypto = new Crypto("Time is an illusion. Lunchtime doubly so.");
+        String expectedOutput = "tasneyinicdsmiohooelntuillibsuuml";
+
+        assertEquals(expectedOutput, crypto.getCipherText());
+    }
+
+    @Test
+    public void normalizedCipherTextIsSplitByHeightOfSquare() {
+        Crypto crypto = new Crypto("Vampires are people too!");
+        String expectedOutput = "vrel aepe mset paoo irpo";
+
+        assertEquals(expectedOutput, crypto.getNormalizedCipherText());
+    }
+
+    @Test
+    public void normalizedCipherNotExactlyDivisibleBy5SpillsIntoSmallerSegment() {
+        Crypto crypto = new Crypto("Madness, and then illumination.");
+        String expectedOutput = "msemo aanin dninn dlaet ltshu i";
+
+        assertEquals(expectedOutput, crypto.getNormalizedCipherText());
+    }
+
+    @Test
+    public void normalizedCipherIsSplitIntoSegmentsOfCorrectSize() {
+        Crypto crypto = new Crypto("If man was meant to stay on the ground god would have given us roots");
+        String expectedOutput = "imtgdvs fearwer mayoogo anouuio ntnnlvt wttddes aohghns seoau";
+
+        assertEquals(expectedOutput, crypto.getNormalizedCipherText());
+    }
+
+    @Test
+    public void normalizedCipherTextIsSplitIntoSegmentsOfCorrectSizeWithPunctuation() {
+        Crypto crypto = new Crypto("Have a nice day. Feed the dog & chill out!");
+        String expectedOutput = "hifei acedl veeol eddgo aatcu nyhht";
+
+        assertEquals(expectedOutput, crypto.getNormalizedCipherText());
+    }
+}