Completed isUnique

README.md

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+# isUnique
+
+### Description
+This repository holds my submission to an assignment for SDEV301 Systems Programming at Green River College. The purpose of this assignment was to review Github forking and provide a light introduction back into algorithms (using Java).
+
+`isUnique` is an algorithm that takes in a given string and returns `true` if all characters in the string are unique and `false` if they are not.
+
+For example:
+- "cat" would return `true`, as all characters in "cat" are unique.
+- "catch" would return `false`, as the character "c" is occurs twice.
+
+### How to Run the Project
+This code can be run as-is with the IntelliJ IDEA IDE from Jetbrains, as long as [Java has been installed](https://www.oracle.com/java/technologies/downloads/) locally.

src/Main.java

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-//TIP To <b>Run</b> code, press <shortcut actionId="Run"/> or
-// click the <icon src="AllIcons.Actions.Execute"/> icon in the gutter.
+/**
+ * SDEV 301: Systems Programming
+ *
+ * @author Kendrick Hang, Tien Han
+ * @version 1.0
+ */
+
+import java.util.ArrayList;
+
 public class Main {
     public static void main(String[] args) {
-        //TIP Press <shortcut actionId="ShowIntentionActions"/> with your caret at the highlighted text
-        // to see how IntelliJ IDEA suggests fixing it.
-        System.out.printf("Hello and welcome!");
+        System.out.print("Hello and welcome!");
 
         for (int i = 1; i <= 5; i++) {
-            //TIP Press <shortcut actionId="Debug"/> to start debugging your code. We have set one <icon src="AllIcons.Debugger.Db_set_breakpoint"/> breakpoint
-            // for you, but you can always add more by pressing <shortcut actionId="ToggleLineBreakpoint"/>.
             System.out.println("i = " + i);
         }
+
+        //Quick Test
+        boolean result = isUnique("always");
+        System.out.println(result);
+        boolean result2 = isUnique("cat");
+        System.out.println(result2);
+    }
+
+    //Another way to do this is to use indexOf("a") and lastIndexOf("a")
+    //If they both return different indexes, then it is not unique
+    //Another way to do this is the "inchworm" technique, where we look at a character
+    //And search through the rest of the string to see if it repeats
+    /**
+     * isUnique checks if all characters in a given string are unique
+     * @param word the given string to test
+     * @return true if string is unique and false if not unique
+     */
+    public static boolean isUnique(String word) {
+        ArrayList<Character> characters = new ArrayList<>();
+
+        for (int i = 0; i < word.length(); i++) {
+            Character character = word.charAt(i);
+            if (characters.contains(character)) {
+                return false;
+            } else {
+                characters.add(character);
+            }
+        }
+        return true;
     }
 }