Hacker Rank_1/54 tests (Easy, Plus Minus)

Given an array of integers, calculate the ratios of its elements that are positive, negative, and zero. Print the decimal value of each fraction on a new line with 6 places after the decimal.

Note: This challenge introduces precision problems. The test cases are scaled to six decimal places, though answers with absolute errors of up to 10(-4) are acceptable.

 

Example

arr = [1, 1, -1, -1, 0]

Results are printed as (the ratios of positive, negative, and zero values):

0.400000
0.400000
0.200000

 

Function Description

Complete the plusMinus function in the editor below.

plusMinus has the following parameter(s):

• int arr[n]: an array of integers

Input Format

The first line contains an integer n, the size of the array.
The second line contains n space-separated integers that describe arr[n].

Constraints

0 < n <= 100

-100 <= arr[i] <= 100

Sample Input

STDIN           Function
-----           --------
6               arr[] size n = 6
-4 3 -9 0 4 1   arr = [-4, 3, -9, 0, 4, 1]

Sample Output

0.500000
0.333333
0.166667

 

---

 

func plusMinus(arr: [Int]) -> Void {
    var ans: [Double] = [0, 0, 0]
    for i in arr {
        if i > 0 {
            ans[0] += 1
        } else if i < 0 {
            ans[1] += 1
        } else {
            ans[2] += 1
        }
    }
    ans[0] = ans[0]/(Double)(arr.count)
    ans[1] = ans[1]/(Double)(arr.count)
    ans[2] = ans[2]/(Double)(arr.count)

    for i in ans {
        print(String(format: "%.6f", i))
    }
}

guard let n = Int((readLine()?.trimmingCharacters(in: .whitespacesAndNewlines))!)
else { fatalError("Bad input") }

guard let arrTemp = readLine()?.replacingOccurrences(of: "\\s+$", with: "", options: .regularExpression) else { fatalError("Bad input") }

let arr: [Int] = arrTemp.split(separator: " ").map {
    if let arrItem = Int($0) {
        return arrItem
    } else { fatalError("Bad input") }
}

guard arr.count == n else { fatalError("Bad input") }

plusMinus(arr: arr)

---

It's a very basic code, but when developing apps, I often lose the basic Swift syntax.

So I plan to complete the one-month kit first. Unlike other test sites, Hacker Rank provides code for the part that receives input values (I'm also attaching this part for study).