+ * The performance of this algorithm can vary: + * - Worst-case performance: O(n) + * - Best-case performance: O(1) + * - Average performance: O(log(log(n))) if the elements are uniformly distributed; otherwise O(n) + * - Worst-case space complexity: O(1) + *
* *- * Worst-case performance O(n) Best-case performance O(1) Average performance - * O(log(log(n))) if the elements are uniformly distributed if not O(n) - * Worst-case space complexity O(1) + * This search algorithm requires the input array to be sorted. + *
* * @author Podshivalov Nikita (https://github.com/nikitap492) */ class InterpolationSearch { /** - * @param array is a sorted array - * @param key is a value what shoulb be found in the array - * @return an index if the array contains the key unless -1 + * Finds the index of the specified key in a sorted array using interpolation search. + * + * @param array The sorted array to search. + * @param key The value to search for. + * @return The index of the key if found, otherwise -1. */ public int find(int[] array, int key) { // Find indexes of two corners @@ -48,23 +54,4 @@ public int find(int[] array, int key) { } return -1; } - - // Driver method - public static void main(String[] args) { - Random r = new Random(); - int size = 100; - int maxElement = 100000; - int[] integers = IntStream.generate(() -> r.nextInt(maxElement)).limit(size).sorted().toArray(); - - // the element that should be found - int shouldBeFound = integers[r.nextInt(size - 1)]; - - InterpolationSearch search = new InterpolationSearch(); - 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/InterpolationSearchTest.java b/src/test/java/com/thealgorithms/searches/InterpolationSearchTest.java new file mode 100644 index 000000000000..b3b7e7ef129c --- /dev/null +++ b/src/test/java/com/thealgorithms/searches/InterpolationSearchTest.java @@ -0,0 +1,90 @@ +package com.thealgorithms.searches; + +import static org.junit.jupiter.api.Assertions.assertEquals; + +import java.util.stream.IntStream; +import org.junit.jupiter.api.Test; + +/** + * Unit tests for the InterpolationSearch class. + */ +class InterpolationSearchTest { + + /** + * Test for basic interpolation search functionality when the element is found. + */ + @Test + void testInterpolationSearchFound() { + InterpolationSearch interpolationSearch = new InterpolationSearch(); + int[] array = {1, 2, 4, 8, 16, 32, 64, 128, 256, 512}; + int key = 128; + int expectedIndex = 7; // Index of the key in the array + assertEquals(expectedIndex, interpolationSearch.find(array, key), "The index of the found element should be 7."); + } + + /** + * Test for interpolation search when the element is not present in the array. + */ + @Test + void testInterpolationSearchNotFound() { + InterpolationSearch interpolationSearch = new InterpolationSearch(); + int[] array = {1, 2, 4, 8, 16}; + int key = 6; // Element not present in the array + assertEquals(-1, interpolationSearch.find(array, key), "The element should not be found in the array."); + } + + /** + * Test for interpolation search with the first element as the key. + */ + @Test + void testInterpolationSearchFirstElement() { + InterpolationSearch interpolationSearch = new InterpolationSearch(); + int[] array = {1, 2, 4, 8, 16}; + int key = 1; // First element + assertEquals(0, interpolationSearch.find(array, key), "The index of the first element should be 0."); + } + + /** + * Test for interpolation search with a single element not present. + */ + @Test + void testInterpolationSearchSingleElementNotFound() { + InterpolationSearch interpolationSearch = new InterpolationSearch(); + int[] array = {1}; + int key = 2; // Key not present + assertEquals(-1, interpolationSearch.find(array, key), "The element should not be found in the array."); + } + + /** + * Test for interpolation search with an empty array. + */ + @Test + void testInterpolationSearchEmptyArray() { + InterpolationSearch interpolationSearch = new InterpolationSearch(); + int[] array = {}; // Empty array + int key = 1; // Key not present + assertEquals(-1, interpolationSearch.find(array, key), "The element should not be found in an empty array."); + } + + /** + * Test for interpolation search on large uniformly distributed array. + */ + @Test + void testInterpolationSearchLargeUniformArray() { + InterpolationSearch interpolationSearch = new InterpolationSearch(); + int[] array = IntStream.range(0, 10000).map(i -> i * 2).toArray(); // Array from 0 to 19998, step 2 + int key = 9998; // Last even number in the array + assertEquals(4999, interpolationSearch.find(array, key), "The index of the last element should be 4999."); + } + + /** + * Test for interpolation search on large non-uniformly distributed array. + */ + @Test + void testInterpolationSearchLargeNonUniformArray() { + InterpolationSearch interpolationSearch = new InterpolationSearch(); + int[] array = {1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144}; // Fibonacci numbers + int key = 21; // Present in the array + assertEquals(6, interpolationSearch.find(array, key), "The index of the found element should be 6."); + } +}