refactor: BoyerMoore (TheAlgorithms#5395)

alxkm · web-flow · commit 35f23d2ddc26 · 2024-08-26T10:33:24.000+03:00
diff --git a/src/main/java/com/thealgorithms/others/BoyerMoore.java b/src/main/java/com/thealgorithms/others/BoyerMoore.java
@@ -1,54 +1,81 @@
-/* this Code is the illustration of Boyer moore's voting algorithm to
-find the majority element is an array that appears more than n/2 times in an array
-where "n" is the length of the array.
-For more information on the algorithm refer
-https://en.wikipedia.org/wiki/Boyer%E2%80%93Moore_majority_vote_algorithm
- */
 package com.thealgorithms.others;
 import java.util.Optional;
 
+/**
+ * Utility class implementing Boyer-Moore's Voting Algorithm to find the majority element
+ * in an array. The majority element is defined as the element that appears more than n/2 times
+ * in the array, where n is the length of the array.
+ *
+ * For more information on the algorithm, refer to:
+ * https://en.wikipedia.org/wiki/Boyer%E2%80%93Moore_majority_vote_algorithm
+ */
 public final class BoyerMoore {
     private BoyerMoore() {
     }
 
-    public static Optional<Integer> findMajor(final int[] a) {
-        final var candidate = findCandidate(a);
-        final var count = countOccurrences(candidate, a);
-        if (isMajority(count, a.length)) {
+    /**
+     * Finds the majority element in the given array if it exists.
+     *
+     * @param array the input array
+     * @return an Optional containing the majority element if it exists, otherwise an empty Optional
+     */
+    public static Optional<Integer> findMajorityElement(int[] array) {
+        if (array == null || array.length == 0) {
+            return Optional.empty();
+        }
+
+        int candidate = findCandidate(array);
+        int count = countOccurrences(candidate, array);
+
+        if (isMajority(count, array.length)) {
             return Optional.of(candidate);
         }
         return Optional.empty();
     }
 
-    private static int findCandidate(final int[] a) {
+    /**
+     * Identifies the potential majority candidate using Boyer-Moore's Voting Algorithm.
+     *
+     * @param array the input array
+     * @return the candidate for the majority element
+     */
+    private static int findCandidate(final int[] array) {
         int count = 0;
         int candidate = -1;
-        for (final var k : a) {
+        for (int value : array) {
             if (count == 0) {
-                candidate = k;
-                count = 1;
-            } else {
-                if (k == candidate) {
-                    count++;
-                } else {
-                    count--;
-                }
+                candidate = value;
             }
+            count += (value == candidate) ? 1 : -1;
         }
         return candidate;
     }
 
-    private static int countOccurrences(final int candidate, final int[] a) {
+    /**
+     * Counts the occurrences of the candidate element in the array.
+     *
+     * @param candidate the candidate element
+     * @param array the input array
+     * @return the number of times the candidate appears in the array
+     */
+    private static int countOccurrences(final int candidate, final int[] array) {
         int count = 0;
-        for (final var j : a) {
-            if (j == candidate) {
+        for (int value : array) {
+            if (value == candidate) {
                 count++;
             }
         }
         return count;
     }
 
-    private static boolean isMajority(final int count, final int totalCount) {
+    /**
+     * Determines if the count of the candidate element is more than n/2, where n is the length of the array.
+     *
+     * @param count the number of occurrences of the candidate
+     * @param totalCount the total number of elements in the array
+     * @return true if the candidate is the majority element, false otherwise
+     */
+    private static boolean isMajority(int count, int totalCount) {
         return 2 * count > totalCount;
     }
 }
diff --git a/src/test/java/com/thealgorithms/others/BoyerMooreTest.java b/src/test/java/com/thealgorithms/others/BoyerMooreTest.java
@@ -11,7 +11,7 @@ public class BoyerMooreTest {
     @ParameterizedTest
     @MethodSource("inputStreamWithExistingMajority")
     void checkWhenMajorityExists(int expected, int[] input) {
-        Assertions.assertEquals(expected, BoyerMoore.findMajor(input).get());
+        Assertions.assertEquals(expected, BoyerMoore.findMajorityElement(input).get());
     }
 
     private static Stream<Arguments> inputStreamWithExistingMajority() {
@@ -21,7 +21,7 @@ private static Stream<Arguments> inputStreamWithExistingMajority() {
     @ParameterizedTest
     @MethodSource("inputStreamWithoutMajority")
     void checkWhenMajorityExists(int[] input) {
-        Assertions.assertFalse(BoyerMoore.findMajor(input).isPresent());
+        Assertions.assertFalse(BoyerMoore.findMajorityElement(input).isPresent());
     }
 
     private static Stream<Arguments> inputStreamWithoutMajority() {
