C#

Question

I had stayed with this question for 10 days🥴
............................................................................
//your code goes here
int result;
foreach(string count in coffee.Keys.ToArray())
{
result=coffee[count]*discount/100;
coffee[count]-=result;
Console.WriteLine(count+": "+ coffee[count]);
}

Answer 1

This should work:
int result;
foreach (string count in coffee.Keys)
{
result=coffee[count] * discount/100;
result = coffee[count] - result;
Console.WriteLine(count+": "+result);
}

The main problem I saw when running your code was that the coffee dictionary was being modified in your foreach which also iterated through coffee. This threw an exception. I replaced storing your calculated result in coffee[count] with storing it in the result variable.

Contrary to what the question says, you actually don't need the .ToArray() so I removed that. It is generally good to follow what the problem says but it is also nice to keep code as clean as possible. Writing clean code is a broader goal outside of the sololearn course so I thought it was best to leave that unnecessary method call out.