Subtract from a number the values to your right in a list

Question

I have a situation that is as follows:

given an array with for example 5 positions [5, 10, 8, 2, 7] I need an algorithm that allows me to do the following:

1. Take the 5 and subtract by the numbers that are after your position [10, 8, 2, 7]

2. Take the 10 and subtract by the numbers that are after your position [8, 2, 7]

3. Take 8 and subtract by the numbers that are after your position [2, 7]

And so on. I need to store the result of these subtractions in a new array.

Can be in either of the two languages.

Answer 1

There is no mystery, just make a loop to go through all elements of the array and within this loop make another loop that goes through all elements after the current and subtract.

There’s nothing piling on it, maybe the array which is received can be used as a stack, but then the logic would be the other way around, ie the first element to be used would be the 7 and the 5 would be the last.

var arr = [5, 10, 8, 2, 7];

for(var i = 0; i < arr.length; i++) {
  var sub = arr[i];
  for(var j = i + 1; j < arr.length; j++) {
    sub -= arr[j];
  }
  
  console.log(arr[i], sub);
}

In C#:

using System;
using static System.Console;                
public class Program
{
    public static void Main()
    {
        var arr = new [] { 5, 10, 8, 2, 7 };

        for(var i = 0; i < arr.Length; i++) 
        {
            var sub = arr[i];
            for(var j = i + 1; j < arr.Length; j++) 
            {
                sub -= arr[j];
            }

            WriteLine($"Elemento: {arr[i]}  Subtração: {sub}");
        }
    }
}

You can see running on . NET Fiddle.