349. 两个数组的交集

**两个数组的交集**

在计算机科学中，两个数组的交集是指两个集合中同时存在的元素。这个问题经常出现在数据处理、信息检索等领域。在本文中，我们将讨论如何求两个数组的交集，并提供相关代码示例。

**算法思路**

求两个数组的交集可以使用以下步骤：

1. 将两个数组合并成一个集合。
2. 使用集合中的元素来构建一个新的集合，这个新集合包含了两个原始集合中同时存在的元素。

**Python代码示例**

def intersection(arr1, arr2):
 """
 Returns the intersection of two arrays.
 Parameters:
 arr1 (list): The first array.
 arr2 (list): The second array.
 Returns:
 list: The intersection of arr1 and arr2.
 """
 # Convert the lists to sets for efficient lookup set1 = set(arr1)
 set2 = set(arr2)
 # Use the & operator to find the intersection intersection_set = set1 & set2 # Convert the result back to a list result = list(intersection_set)
 return result# Example usage:
arr1 = [1,2,3,4,5]
arr2 = [4,5,6,7,8]

print(intersection(arr1, arr2)) # Output: [4,5]

javaimport java.util.*;

public class Main {
 public static Set intersection(int[] arr1, int[] arr2) {
 // Convert the arrays to sets for efficient lookup Set set1 = new HashSet<>();
 for (int num : arr1) {
 set1.add(num);
 }
 Set set2 = new HashSet<>();
 for (int num : arr2) {
 set2.add(num);
 }
 // Use the retainAll method to find the intersection set1.retainAll(set2);
 return set1;
 }

 public static void main(String[] args) {
 int[] arr1 = {1,2,3,4,5};
 int[] arr2 = {4,5,6,7,8};

 Set result = intersection(arr1, arr2);
 System.out.println(result); // Output: [4,5]
 }
}