diff --git a/DIRECTORY.md b/DIRECTORY.md index 23f2941a702c..ff6e29806847 100644 --- a/DIRECTORY.md +++ b/DIRECTORY.md @@ -1006,6 +1006,7 @@ * [HowManyTimesRotatedTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/HowManyTimesRotatedTest.java) * [InterpolationSearchTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/InterpolationSearchTest.java) * [IterativeBinarySearchTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/IterativeBinarySearchTest.java) + * [IterativeTernarySearchTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/IterativeTernarySearchTest.java) * [KMPSearchTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/KMPSearchTest.java) * [OrderAgnosticBinarySearchTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/OrderAgnosticBinarySearchTest.java) * [PerfectBinarySearchTest](https://github.com/TheAlgorithms/Java/blob/master/src/test/java/com/thealgorithms/searches/PerfectBinarySearchTest.java) diff --git a/src/main/java/com/thealgorithms/searches/IterativeTernarySearch.java b/src/main/java/com/thealgorithms/searches/IterativeTernarySearch.java index e78acd6a7ef8..585d6787d3f8 100644 --- a/src/main/java/com/thealgorithms/searches/IterativeTernarySearch.java +++ b/src/main/java/com/thealgorithms/searches/IterativeTernarySearch.java @@ -1,22 +1,26 @@ package com.thealgorithms.searches; import com.thealgorithms.devutils.searches.SearchAlgorithm; -import java.util.Arrays; -import java.util.Random; -import java.util.stream.Stream; /** - * A iterative version of a ternary search algorithm This is better way to - * implement the ternary search, because a recursive version adds some overhead - * to a stack. But in java the compile can transform the recursive version to - * iterative implicitly, so there are no much differences between these two - * algorithms + * An iterative implementation of the Ternary Search algorithm. * *

- * Worst-case performance Θ(log3(N)) Best-case performance O(1) Average - * performance Θ(log3(N)) Worst-case space complexity O(1) + * Ternary search is a divide-and-conquer algorithm that splits the array into three parts + * instead of two, as in binary search. This implementation is iterative, reducing the overhead + * associated with recursive function calls. However, the recursive version can also be optimized + * by the Java compiler to resemble the iterative version, resulting in similar performance. + * + *

+ * Worst-case performance: Θ(log3(N))
+ * Best-case performance: O(1)
+ * Average performance: Θ(log3(N))
+ * Worst-case space complexity: O(1) + * + *

+ * This class implements the {@link SearchAlgorithm} interface, providing a generic search method + * for any comparable type. * - * @author Podshivalov Nikita (https://github.com/nikitap492) * @see SearchAlgorithm * @see TernarySearch * @since 2018-04-13 @@ -25,6 +29,13 @@ public class IterativeTernarySearch implements SearchAlgorithm { @Override public > int find(T[] array, T key) { + if (array == null || array.length == 0 || key == null) { + return -1; + } + if (array.length == 1) { + return array[0].compareTo(key) == 0 ? 0 : -1; + } + int left = 0; int right = array.length - 1; @@ -50,23 +61,4 @@ public > int find(T[] array, T key) { return -1; } - - public static void main(String[] args) { - // just generate data - Random r = new Random(); - int size = 100; - int maxElement = 100000; - Integer[] integers = Stream.generate(() -> r.nextInt(maxElement)).limit(size).sorted().toArray(Integer[] ::new); - - // the element that should be found - Integer shouldBeFound = integers[r.nextInt(size - 1)]; - - IterativeTernarySearch search = new IterativeTernarySearch(); - int atIndex = search.find(integers, shouldBeFound); - - System.out.printf("Should be found: %d. Found %d at index %d. An array length %d%n", shouldBeFound, integers[atIndex], atIndex, size); - - int toCheck = Arrays.binarySearch(integers, shouldBeFound); - System.out.printf("Found by system method at an index: %d. Is equal: %b%n", toCheck, toCheck == atIndex); - } } diff --git a/src/test/java/com/thealgorithms/searches/IterativeTernarySearchTest.java b/src/test/java/com/thealgorithms/searches/IterativeTernarySearchTest.java new file mode 100644 index 000000000000..c7640e6d0672 --- /dev/null +++ b/src/test/java/com/thealgorithms/searches/IterativeTernarySearchTest.java @@ -0,0 +1,117 @@ +package com.thealgorithms.searches; + +import static org.junit.jupiter.api.Assertions.assertEquals; + +import org.junit.jupiter.api.Test; + +/** + * Unit tests for the IterativeTernarySearch class. + */ +class IterativeTernarySearchTest { + + /** + * Test for basic ternary search functionality when the element is found. + */ + @Test + void testTernarySearchFound() { + IterativeTernarySearch ternarySearch = new IterativeTernarySearch(); + Integer[] array = {1, 2, 4, 8, 16, 32, 64, 128, 256, 512}; + Integer key = 128; + int expectedIndex = 7; // Index of the key in the array + assertEquals(expectedIndex, ternarySearch.find(array, key), "The index of the found element should be 7."); + } + + /** + * Test for ternary search when the element is not present in the array. + */ + @Test + void testTernarySearchNotFound() { + IterativeTernarySearch ternarySearch = new IterativeTernarySearch(); + Integer[] array = {1, 2, 4, 8, 16}; + Integer key = 6; // Element not present in the array + assertEquals(-1, ternarySearch.find(array, key), "The element should not be found in the array."); + } + + /** + * Test for ternary search with the first element as the key. + */ + @Test + void testTernarySearchFirstElement() { + IterativeTernarySearch ternarySearch = new IterativeTernarySearch(); + Integer[] array = {1, 2, 4, 8, 16}; + Integer key = 1; // First element + assertEquals(0, ternarySearch.find(array, key), "The index of the first element should be 0."); + } + + /** + * Test for ternary search with the last element as the key. + */ + @Test + void testTernarySearchLastElement() { + IterativeTernarySearch ternarySearch = new IterativeTernarySearch(); + Integer[] array = {1, 2, 4, 8, 16}; + Integer key = 16; // Last element + assertEquals(4, ternarySearch.find(array, key), "The index of the last element should be 4."); + } + + /** + * Test for ternary search with a single element present. + */ + @Test + void testTernarySearchSingleElementFound() { + IterativeTernarySearch ternarySearch = new IterativeTernarySearch(); + Integer[] array = {1}; + Integer key = 1; // Only element present + assertEquals(0, ternarySearch.find(array, key), "The index of the single element should be 0."); + } + + /** + * Test for ternary search with a single element not present. + */ + @Test + void testTernarySearchSingleElementNotFound() { + IterativeTernarySearch ternarySearch = new IterativeTernarySearch(); + Integer[] array = {1}; + Integer key = 2; // Key not present + assertEquals(-1, ternarySearch.find(array, key), "The element should not be found in the array."); + } + + /** + * Test for ternary search with an empty array. + */ + @Test + void testTernarySearchEmptyArray() { + IterativeTernarySearch ternarySearch = new IterativeTernarySearch(); + Integer[] array = {}; // Empty array + Integer key = 1; // Key not present + assertEquals(-1, ternarySearch.find(array, key), "The element should not be found in an empty array."); + } + + /** + * Test for ternary search on a large array. + */ + @Test + void testTernarySearchLargeArray() { + IterativeTernarySearch ternarySearch = new IterativeTernarySearch(); + Integer[] array = new Integer[10000]; + for (int i = 0; i < array.length; i++) { + array[i] = i * 2; + } // Array from 0 to 19998, step 2 + Integer key = 9998; // Present in the array + assertEquals(4999, ternarySearch.find(array, key), "The index of the found element should be 4999."); + } + + /** + * Test for ternary search on large array with a non-existent key. + */ + @Test + void testTernarySearchLargeArrayNotFound() { + IterativeTernarySearch ternarySearch = new IterativeTernarySearch(); + Integer[] array = new Integer[10000]; + for (int i = 0; i < array.length; i++) { + array[i] = i * 2; + } // Array from 0 to 19998, step 2 + Integer key = 9999; // Key not present + assertEquals(-1, ternarySearch.find(array, key), "The element should not be found in the array."); + } +}