Golang における配列交差の効率的なアルゴリズム

func intersect_naive(arr1, arr2 []int) []int {
    result := []int{}
    for i := 0; i < len(arr1); i++ {
        for j := 0; j < len(arr2); j++ {
            if arr1[i] == arr2[j] {
                result = append(result, arr1[i])
            }
        }
    }
    return result
}

func intersect_binary_search(arr1, arr2 []int) []int {
    result := []int{}
    for _, v := range arr1 {
        if exists := binarySearch(arr2, v); exists {
            result = append(result, v)
        }
    }
    return result
}

func binarySearch(arr []int, target int) bool {
    left, right := 0, len(arr)-1

    for left <= right {
        mid := left + (right-left)/2
        if arr[mid] == target {
            return true
        } else if arr[mid] < target {
            left = mid + 1
        } else {
            right = mid - 1
        }
    }
    return false
}

func intersect_map(arr1, arr2 []int) []int {
    result := []int{}
    m := make(map[int]int)

    for _, v := range arr1 {
        m[v]++
    }

    for _, v := range arr2 {
        if count, ok := m[v]; ok {
            result = append(result, v)
            count--
            if count == 0 {
                delete(m, v)
            } else {
                m[v] = count
            }
        }
    }
    return result
}

arr1 := []int{1, 2, 3, 4, 5}
arr2 := []int{3, 4, 5, 6, 7}

result := intersect_map(arr1, arr2)
fmt.Println(result) // 输出：[3, 4, 5]