compare linq and dict on performance for finding duplicates in a string array.

linqvsdict-to-find-duplicates.cs

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

namespace rnd
{
    class Program
    {
        static void Main(string[] args)
        {
            string sentence = "This is a test for duplicate arrays to test performance of different solution approaches some words in this sentence are duplicate while the others are not duplicate. The test is to see whether the linq based approach takes more time or whether the dictionary based approach takes more time to process over a million iterations";
            var array = sentence.Split(" ");
            
            var linqwatch = new Stopwatch();
            var dictwatch = new Stopwatch();

            linqwatch.Start();
            for (int i = 0; i < 1000000; i++)
            {
                PrintDuplicatesLinq(array);
            }
            linqwatch.Stop();

            dictwatch.Start();
            for (int i = 0; i < 1000000; i++)
            {
                PrintDuplicatesDict(array);
            }
            dictwatch.Stop();

            Console.WriteLine($"Linq time: {linqwatch.ElapsedMilliseconds}, Dict time: {dictwatch.ElapsedMilliseconds}");
            
        }

        public static void PrintDuplicatesLinq(string[] stringArray){
            var duplicates = stringArray.ToList().GroupBy(x => x)
              .Where(g => g.Count() > 1)
              .Select(y => y.Key)
              .ToList();
            
            duplicates.ForEach(x=>{Console.WriteLine(x);});
        }

        public static void PrintDuplicatesDict(string[] stringArray){
            Dictionary<string, int> wordslist = new Dictionary<string, int>();
            foreach (var item in stringArray)
            {
                if (wordslist.ContainsKey(item)){
                    Console.WriteLine(item);
                }else{
                    wordslist[item] = 1;
                }
            }
        }
    }
}