Program Code

package main

import (
    "fmt"
)

// unionIntersection takes two slices of integers and returns their union and intersection.
func unionIntersection(arr1, arr2 []int) ([]int, []int) {
    // Use maps to track unique elements
    elementMap := make(map[int]bool)
    intersection := make([]int, 0)

    // Add elements of the first array to the map
    for _, num := range arr1 {
        elementMap[num] = true
    }

    // Prepare to collect the union
    union := make([]int, 0, len(arr1)+len(arr2))

    // Process the second array
    for _, num := range arr2 {
        // Check for union
        if _, exists := elementMap[num]; !exists {
            union = append(union, num)
        } else {
            // If it exists in both, it's part of the intersection
            intersection = append(intersection, num)
        }
    }

    // Append the unique elements from the first array to union
    for num := range elementMap {
        union = append(union, num)
    }

    return union, intersection
}

func main() {
    arr1 := []int{1, 2, 3, 4, 5}
    arr2 := []int{4, 5, 6, 7, 8}

    union, intersection := unionIntersection(arr1, arr2)

    fmt.Println("Union:", union)
    fmt.Println("Intersection:", intersection)
}

Explanation of the Program Structure

The program consists of a main function and a helper function called unionIntersection.

1. Imports

The program imports the fmt package, which is used for formatted I/O operations.

2. unionIntersection Function

This function takes two slices of integers as input and returns two slices: one for the union and one for the intersection.

• elementMap: A map is created to store unique elements from the first array.
• intersection: A slice to hold elements that exist in both arrays.
• The first loop populates elementMap with elements from arr1.
• The second loop processes arr2. If an element is not in elementMap, it’s added to the union; if it exists, it’s added to the intersection.
• Finally, elements from elementMap are appended to the union slice.

3. Main Function

The main function initializes two arrays and calls the unionIntersection function. The results are then printed to the console.

Conclusion

This program efficiently calculates the union and intersection of two integer arrays using hashing, ensuring unique values are processed effectively.