**JAVA **

int length = arr.size(); int countPositive = 0; int countNegative = 0; int countZeroes = 0;

for(int i : arr){
    if(i > 0){
        countPositive++;
    } else if(i < 0){
        countNegative++;
    } else{
        countZeroes++;
    }
}

    double positiveRatio = (double) countPositive / length;
    double negativeRatio = (double) countNegative / length;
    double zeroRatio = (double) countZeroes / length;

    System.out.println(String.format("%.6f", positiveRatio));
    System.out.println(String.format("%.6f", negativeRatio));
    System.out.println(String.format("%.6f", zeroRatio));

Depending on the size of the dataset, it can use CompletableFuture or even a ThreadPool (in C# TPL for async and parallel tasks as well). But this task is quite simple, so it would not be required

public static void plusMinus(List arr) { var total = arr.Count(); var positives = arr.Where(p => p > 0).ToList(); Console.WriteLine(CalculateInputRatio(positives.Count, total));

    var negatives = arr.Where(p => p < 0).ToList();
    Console.WriteLine(CalculateInputRatio(negatives.Count, total));

    var xeros = arr.Where(p => p == 0).ToList();
    Console.WriteLine(CalculateInputRatio(xeros.Count, total));

}

private static string CalculateInputRatio(int numbersCount, int total)
{
    decimal ratio = (decimal)numbersCount/total;
    return ratio.ToString("F6");
}

let final ={p:0,n:0,z:0}; for(let i of arr){ if(i===0){ final['z']=(final['z']||0) +1; } if(i<0){ final['n']=(final['n']||0) +1; } if(i>0){ final['p']=(final['p']||0) +1; } } Object.values(final).map(item=>console.log(item/arr.length))