Merge branch 'master' of https://github.com/DatMV01/Algorithms-and-Data-Structures-in-Java

Author: DatMV01

src/main/java/com/ctci/arraysandstrings/IsUnique.java

@@ -6,16 +6,33 @@
  */
 public class IsUnique {
 
-    private static boolean hasAllUniqueCharacters(String str) {
-        if (str == null || str.length() > 128) return false;
+    /**
+     * Check whether the input string contains different individual characters and it in the ASCII table.
+     *
+     * @param str Input string
+     * @return true if all characters are different from each other, otherwise false.
+     */
+    public static boolean isAllCharactersUniqueAndInASCII(String str) {
+        if (str == null || str.isEmpty()) {
+            return false;
+        }
+
+        int maxCharIndex = 128;
+        int stringLength = str.length();
 
-        boolean[] charSet = new boolean[128]; // assuming the string contains only ASCII characters
-        for (int i = 0; i < str.length(); i++) {
-            int charVal = str.charAt(i);
-            if (charSet[charVal]) {
+        if (stringLength > maxCharIndex) {
+            return false;
+        }
+
+        boolean[] characterTrack = new boolean[maxCharIndex]; // assuming the string contains only ASCII characters
+        for (int i = 0; i < stringLength; i++) {
+            int charIndex = str.charAt(i);
+            if (charIndex >= maxCharIndex
+                    || characterTrack[charIndex]) {
                 return false;
             }
-            charSet[charVal] = true;
+
+            characterTrack[charIndex] = true;
         }
         return true;
     }
@@ -34,11 +51,11 @@ private static boolean hasAllUniqueCharactersWhenStringContainsAllLowercase(Stri
 
     public static void main(String[] args) {
         String s = "ram";
-        System.out.println(hasAllUniqueCharacters(s));
+        System.out.println(isAllCharactersUniqueAndInASCII(s));
         s = "rama";
-        System.out.println(hasAllUniqueCharacters(s));
+        System.out.println(isAllCharactersUniqueAndInASCII(s));
         s = "ramA";
-        System.out.println(hasAllUniqueCharacters(s));
+        System.out.println(isAllCharactersUniqueAndInASCII(s));
         System.out.println("-------");
         s = "ram";
         System.out.println(hasAllUniqueCharactersWhenStringContainsAllLowercase(s));

src/main/test/com/ctci/arraysandstrings/IsUniqueTest.java

@@ -0,0 +1,112 @@
+package com.ctci.arraysandstrings;
+
+import org.junit.jupiter.api.*;
+
+public class IsUniqueTest {
+
+    @Nested
+    @DisplayName("Test cases for isAllCharactersUniqueAndInASCII()")
+    class TestCasesForIsAllCharactersUniqueAndInASCII{
+
+        @Test
+        public void isAllCharactersUniqueAndInASCII_StringIsNull_ReturnFalse() {
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII(null));
+        }
+
+        @Test
+        public void isAllCharactersUniqueAndInASCII_StringIsEmpty_ReturnFalse() {
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII(""));
+        }
+
+        @Test
+        public void isAllCharactersUniqueAndInASCII_StringLengthSmallerOrEqual128_ReturnFalse() {
+            StringBuilder stringBuilder = new StringBuilder();
+
+            for (int i = 0; i < 128; i++) {
+                stringBuilder.append((char) i);
+            }
+            Assertions.assertTrue(IsUnique.isAllCharactersUniqueAndInASCII(stringBuilder.toString()));
+
+            stringBuilder.setLength(0);
+            for (int i = 1; i < 127; i++) {
+                stringBuilder.append((char) i);
+            }
+            Assertions.assertTrue(IsUnique.isAllCharactersUniqueAndInASCII(stringBuilder.toString()));
+        }
+
+        @Test
+        public void isAllCharactersUniqueAndInASCII_StringLengthLargerThan128_ReturnFalse() {
+            StringBuilder stringBuilder = new StringBuilder();
+
+            for (int i = 0; i < 128; i++) {
+                stringBuilder.append((char) i);
+            }
+            stringBuilder.append("a");
+
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII(stringBuilder.toString()));
+        }
+
+        @Test
+        public void isAllCharactersUniqueAndInASCII_DuplicateAtHead_ReturnFalse() {
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("aab"));
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("AAb"));
+
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("ááb"));
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("ÁÁb"));
+
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("1123456"));
+        }
+
+        @Test
+        public void isAllCharactersUniqueAndInASCII_DuplicateAtMiddle_ReturnFalse() {
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("abcbd"));
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("aBcBd"));
+
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("aưcưd"));
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("aƯcƯd"));
+
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("123436"));
+        }
+
+        @Test
+        public void isAllCharactersUniqueAndInASCII_DuplicateAtTail_ReturnFalse() {
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("aba"));
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("AbA"));
+
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("ăbă"));
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("ĂbĂ"));
+
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("1234566"));
+        }
+
+        @Test
+        public void isAllCharactersUniqueAndInASCII_OnlyOneCharacter_ReturnTrue() {
+            Assertions.assertTrue(IsUnique.isAllCharactersUniqueAndInASCII("a"));
+            Assertions.assertTrue(IsUnique.isAllCharactersUniqueAndInASCII("1"));
+            Assertions.assertTrue(IsUnique.isAllCharactersUniqueAndInASCII("A"));
+            Assertions.assertTrue(IsUnique.isAllCharactersUniqueAndInASCII("#"));
+        }
+
+        @Test
+        public void isAllCharactersUniqueAndInASCII_OnlyOneCharacter_ReturnFalse() {
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("á"));
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("Ô"));
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("€"));
+        }
+
+        @Test
+        public void isAllCharactersUniqueAndInASCII_InvalidString_ReturnFalse() {
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("ۇ"));
+            Assertions.assertFalse(IsUnique.isAllCharactersUniqueAndInASCII("áÂ"));
+        }
+
+        @Test
+        public void isAllCharactersUniqueAndInASCII_ValidString_ReturnTrue() {
+            Assertions.assertTrue(IsUnique.isAllCharactersUniqueAndInASCII("aAb"));
+            Assertions.assertTrue(IsUnique.isAllCharactersUniqueAndInASCII("abcBd"));
+            Assertions.assertTrue(IsUnique.isAllCharactersUniqueAndInASCII("abA"));
+            Assertions.assertTrue(IsUnique.isAllCharactersUniqueAndInASCII(
+                    "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"));
+        }
+    }
+}