using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;
 
public class Test
{
	public static void Main()
	{
		var dct = new Dictionary<string, string>();
		dct.Add("bla", "boo");
		dct.Add("bla test", "ZZZ");
		var pat = $@"\b(https://\S+|www\.\S+)|(?:{string.Join("|",dct.Keys.Select(k => Regex.Escape(k)).OrderByDescending(x => x.Length))})";
		Console.WriteLine(pat);
		var input ="bla bla test test1 test3. Go to www.something.com/bla/something";
		var output = Regex.Replace(input, pat, m => m.Groups[1].Success ? m.Groups[1].Value : dct[m.Value]); 
		Console.Write(output);
 
		//var output = "boo boo test test1 test3...";
	}
}

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