From dfa504b51b01f4571b19da754265b10ad0d6886b Mon Sep 17 00:00:00 2001
From: alxkm
- * This class utilizes a HashMap to efficiently count occurrences of elements in the first array,
- * allowing for an efficient lookup of common elements in the second array.
+ * This intersection includes duplicate values — meaning elements are included in the result
+ * as many times as they appear in both arrays (i.e., multiset intersection).
*
- * Example:
- *
+ * The algorithm uses a {@link java.util.HashMap} to count occurrences of elements in the first array,
+ * then iterates through the second array to collect common elements based on these counts.
+ *
+ * Example usage: + *
{@code * int[] array1 = {1, 2, 2, 1}; * int[] array2 = {2, 2}; - * List+ * Listresult = Intersection.intersection(array1, array2); // result will contain [2, 2] - *
- * Note: The order of the returned list may vary since it depends on the order of elements - * in the input arrays. + * Note: The order of elements in the returned list depends on the order in the second input array. *
*/ public final class Intersection { + private Intersection() { + // Utility class; prevent instantiation + } + /** - * Computes the intersection of two integer arrays. + * Computes the intersection of two integer arrays, preserving element frequency. + * For example, given [1,2,2,3] and [2,2,4], the result will be [2,2]. + * * Steps: - * 1. Count the occurrences of each element in the first array using a HashMap. - * 2. Iterate over the second array and check if the element is present in the HashMap. - * If it is, add it to the result list and decrement the count in the HashMap. - * 3. Return the result list containing the intersection of the two arrays. + * 1. Count the occurrences of each element in the first array using a map. + * 2. Iterate over the second array and collect common elements. * * @param arr1 the first array of integers * @param arr2 the second array of integers - * @return a list containing the intersection of the two arrays, or an empty list if either array is null or empty + * @return a list containing the intersection of the two arrays (with duplicates), + * or an empty list if either array is null or empty */ public static ListNote: This service is not intended for secure transactions such as banking, social media, email, or purchasing. Use at your own risk. We assume no liability whatsoever for broken pages.
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