Question

I’m training with solving Olympic IT-riddles on one site.

I have provided two solutions:

 - C# 

http://ideone.com/exF1HJ

 - PHP 

http://ideone.com/WbaPHY

I was confused when online judgment showed , that PHP version was faster!!!
Why?

C#: 109 ms 3000 Kb

PHP: 45 ms 0 Kb

How could it be?

Answer 1

Your C# version creates three arrays that you don’t seem to need. You could replace it with:

string input = Console.ReadLine();
int charCount = input.Distinct().Count();
if(charCount % 2 == 0) ...

The following is probably quicker still:

int charCount = new HashSet<char>(input).Count;