I am trying to write a test case in my main function for the following code that is used to find the product and sum of a nested array:

package main

import "fmt"

type SpecialArray []interface{}

func ProductSum(array SpecialArray) int {
        return helper(array, 1)
}

func helper(array SpecialArray, multiplier int) int {
        sum := 0
        for _, el := range array {
                if cast, ok := el.(SpecialArray); ok {
                        sum  = helper(cast, multiplier   1)
                } else if cast, ok := el.(int); ok {
                        sum  = cast
                }
        }
        return sum * multiplier

}

Given a nested array with a mix of ints and arrays, the above code should return the sum of all elements. Elements within a nested array will be summed then multiplied by their depth, i.e.,

[1, [2, 3], 2] = 1 2(2 3) 2 = 13

I am having trouble understanding the SpecialArray []interface{} type. My first attempt was to simply define a nested slice in my main function as follows:

func main() {
        SpecialArray := [][]int{1, {2, 3}, 2}
        result := ProductSum(SpecialArray)
        fmt.Println(result)
}

But this is not working. I'm assuming I need to initalize my SpecialArray interface with values and pass that to my ProductSum function.

CodePudding user response：

You are very close but did not quite get the array literal syntax right:

func main() {
    special := SpecialArray{1, SpecialArray{2, 3}, 2}
    result := ProductSum(special)
    fmt.Println(result)
}

Also your helper function is fine as is but you might consider using a type switch:

func helper(array SpecialArray, multiplier int) int {
    sum := 0
    for _, v := range array {
        switch v := v.(type) {
        case int:
            sum  = v
        case SpecialArray:
            sum  = helper(v, multiplier 1)
        default:
            log.Fatalf("Unknown type: %T", v)
        }
    }
    return sum * multiplier
}

BTW the SpecialArray type is a slice not an array.