diff --git a/src/main/java/com/thealgorithms/bitmanipulation/SingleElement.java b/src/main/java/com/thealgorithms/bitmanipulation/SingleElement.java new file mode 100644 index 000000000..85ebdf02d --- /dev/null +++ b/src/main/java/com/thealgorithms/bitmanipulation/SingleElement.java @@ -0,0 +1,39 @@ +package com.thealgorithms.bitmanipulation; + +/** + * Utility class to find the single non-duplicate element from an array + * where all other elements appear twice. + *

+ * The algorithm runs in O(n) time complexity and O(1) space complexity + * using bitwise XOR. + *

+ * + * @author Tuhin M + */ +public final class SingleElement { + + /** + * Private constructor to prevent instantiation of this utility class. + * Throws an UnsupportedOperationException if attempted. + */ + private SingleElement() { + throw new UnsupportedOperationException("Utility Class"); + } + + /** + * Finds the single non-duplicate element in an array where every other + * element appears exactly twice. Uses bitwise XOR to achieve O(n) time + * complexity and O(1) space complexity. + * + * @param arr the input array containing integers where every element + * except one appears exactly twice + * @return the single non-duplicate element + */ + public static int findSingleElement(int[] arr) { + int ele = 0; + for (int i = 0; i < arr.length; i++) { + ele ^= arr[i]; + } + return ele; + } +} diff --git a/src/test/java/com/thealgorithms/bitmanipulation/SingleElementTest.java b/src/test/java/com/thealgorithms/bitmanipulation/SingleElementTest.java new file mode 100644 index 000000000..2e2afe99b --- /dev/null +++ b/src/test/java/com/thealgorithms/bitmanipulation/SingleElementTest.java @@ -0,0 +1,33 @@ +package com.thealgorithms.bitmanipulation; + +import static org.junit.jupiter.api.Assertions.assertEquals; + +import java.util.stream.Stream; +import org.junit.jupiter.params.ParameterizedTest; +import org.junit.jupiter.params.provider.Arguments; +import org.junit.jupiter.params.provider.MethodSource; + +public final class SingleElementTest { + + /** + * Parameterized test to find the single non-duplicate element + * in the given arrays. + * + * @param arr the input array where every element appears twice except one + * @param expected the expected single element result + */ + @ParameterizedTest + @MethodSource("provideTestCases") + void testFindSingleElement(int[] arr, int expected) { + assertEquals(expected, SingleElement.findSingleElement(arr)); + } + + /** + * Provides test cases for the parameterized test. + * + * @return Stream of arguments consisting of arrays and expected results + */ + private static Stream provideTestCases() { + return Stream.of(Arguments.of(new int[] {1, 1, 2, 2, 4, 4, 3}, 3), Arguments.of(new int[] {1, 2, 2, 3, 3}, 1), Arguments.of(new int[] {10}, 10)); + } +}