using System;
using System.Diagnostics;
using System.Collections.Generic;
using System.Linq;

public class Test
{
	public static void Main()
	{
		var str = "abcdefghijklmnopqrstuvwxyz";
		var r = new Random();
		var sourceList = Enumerable.Range(0,1000000).Select(n=>str[r.Next(str.Length)].ToString()).ToArray();
		
		var sw = new Stopwatch();
		
		sw.Start();
		var outList = new List<string>();
		for(int i = 0; i < sourceList.Length; i++){
			if(sourceList[i] == "a" || sourceList[i] == "b"){
				outList.Add(sourceList[i]);
			}
		}
		sw.Stop();
		Console.WriteLine("for : " + sw.Elapsed);

		sw.Reset();
		sw.Start();
		var outList2 = sourceList.Where(s=>s=="a" || s=="b").ToList();
		sw.Stop();
		Console.WriteLine("linq: " + sw.Elapsed);
	}
}