Repository: TheAlgorithms/Java
Pull request #3807 (2023-01-09 09:09:01)

add the conway sequence
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- [ ] I have read [CONTRIBUTING.md](https://github.com/TheAlgorithms/Java/blob/master/CONTRIBUTING.md).
- [ ] This pull request is all my own work -- I have not plagiarized it.
- [ ] All filenames are in PascalCase.
- [ ] All functions and variable names follow Java naming conventions.
- [ ] All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.


eloibru: Done, I've added a few tests.


Patch:
diff --git a/src/main/java/com/thealgorithms/others/Conway.java b/src/main/java/com/thealgorithms/others/Conway.java
new file mode 100644
index 00000000..7a034d96
--- /dev/null
+++ b/src/main/java/com/thealgorithms/others/Conway.java
@@ -0,0 +1,36 @@
+package com.thealgorithms.others;
+
+import java.util.*;
+
+public class Conway {
+
+    /*
+     * This class will generate the conway sequence also known as the look and say sequence.
+     * To generate a member of the sequence from the previous member, read off the digits of the previous member, counting the number of digits in groups of the same digit. For example:
+     *1 is read off as "one 1" or 11.
+     *11 is read off as "two 1s" or 21.
+     *21 is read off as "one 2, one 1" or 1211.
+     *1211 is read off as "one 1, one 2, two 1s" or 111221.
+     *111221 is read off as "three 1s, two 2s, one 1" or 312211.
+     * https://en.wikipedia.org/wiki/Look-and-say_sequence
+     * */
+
+    private static final StringBuilder builder = new StringBuilder();
+
+    protected static List<String> generateList(String originalString, int maxIteration) {
+        List<String> numbers = new ArrayList<>();
+        for(int i=0; i<maxIteration; i++) {
+            originalString = generateNextElement(originalString);
+            numbers.add(originalString);
+        }
+        return numbers;
+    }
+
+
+    public static String generateNextElement(String originalString) {
+        builder.setLength(0);
+        String[] stp = originalString.split("(?<=(.))(?!\\1)");
+        Arrays.stream(stp).forEach(s -> builder.append(s.length()).append(s.charAt(0)));
+        return builder.toString();
+    }
+}


Test patch:
diff --git a/src/test/java/com/thealgorithms/others/ConwayTest.java b/src/test/java/com/thealgorithms/others/ConwayTest.java
new file mode 100644
index 00000000..04b35794
--- /dev/null
+++ b/src/test/java/com/thealgorithms/others/ConwayTest.java
@@ -0,0 +1,37 @@
+package com.thealgorithms.others;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class ConwayTest {
+    @Test
+    public void testGenerateWith1(){
+        assertEquals("31131211131221", Conway.generateList("1", 8).get(7));
+    }
+
+    @Test
+    public void testGenerateWith123456(){
+        assertEquals("13211321322113311213212312311211131122211213211331121321122112133221123113112221131112212211131221121321131211132221123113112221131112311332211211131221131211132211121312211231131112311211232221143113112221131112311332111213122112311311123112112322211531131122211311123113321112131221123113111231121123222116", Conway.generateList("123456", 20).get(11));
+    }
+
+    @Test
+    public void testGenerateWith1A1Z3E1R1T3G1F1D2E1S1C(){
+        assertEquals("311311222113111231133211121312211231131112311211133112111312211213211312111322211231131122111213122112311311222112111331121113112221121113122113121113222112132113213221232112111312111213322112311311222113111221221113122112132113121113222112311311222113111231133221121113311211131122211211131221131112311332211211131221131211132221232112111312111213322112132113213221133112132113221321123113213221121113122123211211131221222112112322211231131122211311123113321112132132112211131221131211132221121321132132212321121113121112133221123113112221131112311332111213211322111213111213211231131211132211121311222113321132211221121332211A311311222113111231133211121312211231131112311211133112111312211213211312111322211231131122111213122112311311222112111331121113112221121113122113121113222112132113213221232112111312111213322112311311222113111221221113122112132113121113222112311311222113111231133221121113311211131122211211131221131112311332211211131221131211132221232112111312111213322112132113213221133112132113221321123113213221121113122123211211131221222112112322211231131122211311123113321112132132112211131221131211132221121321132132212321121113121112133221123113112221131112311332111213211322111213111213211231131211132211121311222113321132211221121332211Z111312211312111322212321121113121112131112132112311321322112111312212321121113122112131112131221121321132132211231131122111213122112311311222113111221131221221321132132211331121321231231121113112221121321133112132112211213322112311311222113111231133211121312211231131122211322311311222112111312211311123113322112132113212231121113112221121321132122211322212221121123222112111312211312111322212321121113121112131112132112311321322112111312212321121113122112131112131221121321132132211231131122211331121321232221121113122113121122132112311321322112111312211312113221133211322112211213322112132113213221133112132123123112111311222112132113311213211231232112311311222112111312211311123113322112132113213221133112132123222113221321132132211331121321232221123113112221131112311322311211131122211213211331121321122112133221121113122113121113222123112221221321132132211231131122211331121321232221121113122113121113222123113221231231121113213221231221132221222112112322211E311311222113111231133211121312211231131112311211133112111312211213211312111322211231131122111213122112311311222112111331121113112221121113122113121113222112132113213221232112111312111213322112311311222113111221221113122112132113121113222112311311222113111231133221121113311211131122211211131221131112311332211211131221131211132221232112111312111213322112132113213221133112132113221321123113213221121113122123211211131221222112112322211231131122211311123113321112132132112211131221131211132221121321132132212321121113121112133221123113112221131112311332111213211322111213111213211231131211132211121311222113321132211221121332211R311311222113111231133211121312211231131112311211133112111312211213211312111322211231131122111213122112311311222112111331121113112221121113122113121113222112132113213221232112111312111213322112311311222113111221221113122112132113121113222112311311222113111231133221121113311211131122211211131221131112311332211211131221131211132221232112111312111213322112132113213221133112132113221321123113213221121113122123211211131221222112112322211231131122211311123113321112132132112211131221131211132221121321132132212321121113121112133221123113112221131112311332111213211322111213111213211231131211132211121311222113321132211221121332211T111312211312111322212321121113121112131112132112311321322112111312212321121113122112131112131221121321132132211231131122111213122112311311222113111221131221221321132132211331121321231231121113112221121321133112132112211213322112311311222113111231133211121312211231131122211322311311222112111312211311123113322112132113212231121113112221121321132122211322212221121123222112111312211312111322212321121113121112131112132112311321322112111312212321121113122112131112131221121321132132211231131122211331121321232221121113122113121122132112311321322112111312211312113221133211322112211213322112132113213221133112132123123112111311222112132113311213211231232112311311222112111312211311123113322112132113213221133112132123222113221321132132211331121321232221123113112221131112311322311211131122211213211331121321122112133221121113122113121113222123112221221321132132211231131122211331121321232221121113122113121113222123113221231231121113213221231221132221222112112322211G311311222113111231133211121312211231131112311211133112111312211213211312111322211231131122111213122112311311222112111331121113112221121113122113121113222112132113213221232112111312111213322112311311222113111221221113122112132113121113222112311311222113111231133221121113311211131122211211131221131112311332211211131221131211132221232112111312111213322112132113213221133112132113221321123113213221121113122123211211131221222112112322211231131122211311123113321112132132112211131221131211132221121321132132212321121113121112133221123113112221131112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Conway.generateList("1A1Z3E1R1T3G1F1D2E1S1C", 20).get(19));
+    }
+
+    @Test
+    public void testGenerateNextElementWith1(){
+        assertEquals("11", Conway.generateNextElement("1"));
+    }
+
+    @Test
+    public void testGenerateNextElementWith123456(){
+        assertEquals("111213141516", Conway.generateNextElement("123456"));
+    }
+
+    @Test
+    public void testGenerateNextElementWith1A1Z3E1R1T3G1F1D2E1S1C(){
+        assertEquals("111A111Z131E111R111T131G111F111D121E111S111C", Conway.generateNextElement("1A1Z3E1R1T3G1F1D2E1S1C"));
+    }
+}