C# Algorithms – Phone Book Implementation – List of int and string with a tuple

Today I had to write a solution of the following problem – imagine you have two lists like this:

		var liPhoneBook = new List<tuple<int,string>>();
		liPhoneBook.Add(Tuple.Create(100, "Pesho"));
		liPhoneBook.Add(Tuple.Create(200, "Gosho"));
		liPhoneBook.Add(Tuple.Create(300, "Atanas"));
		liPhoneBook.Add(Tuple.Create(400, "Az"));
		liPhoneBook.Add(Tuple.Create(500, "Ivan"));
		liPhoneBook.Add(Tuple.Create(600, "Ivan Petrov"));
		liPhoneBook.Add(Tuple.Create(900, "Vitosh"));


		List  liNumbers = new List (new int[]{900, 300,400,100,600});

What I needed to write was a program, printing the names of the users in liNumbers. Something like this. As far as using two embedded loops was pretty much the obvious solution, I have decided to go one step further and to optimize it … After all, this is algorithm implementation. Thus, I have decided to still use the two loops, but to start the inner loop only from the index which I have reached so far. As you see, in the printed version I am printing the indices of the inner loop and they do not repeat. Thus, it works better than just two loops. 🙂

So far so good! Here comes the code:

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


class MainClass
{
	public static void Main ()
	{
		var liPhoneBook = new List<tuple<int,string>>();
		liPhoneBook.Add(Tuple.Create(100, "Pesho"));
		liPhoneBook.Add(Tuple.Create(200, "Gosho"));
		liPhoneBook.Add(Tuple.Create(300, "Atanas"));
		liPhoneBook.Add(Tuple.Create(400, "Az"));
		liPhoneBook.Add(Tuple.Create(500, "Ivan"));
		liPhoneBook.Add(Tuple.Create(600, "Ivan Petrov"));
		liPhoneBook.Add(Tuple.Create(900, "Vitosh"));


		List  liNumbers = new List (new int[]{900, 300,400,100,600});
		findNumbers (liNumbers, liPhoneBook);
	}

	public static void findNumbers(List liNumbers, List<tuple<int,string>> liPhoneBook)
	{
		liNumbers.Sort ();
		liPhoneBook.Sort ();
		int iPosition = 0;

		foreach (var item in liNumbers) {
			for (int i = iPosition; i < liPhoneBook.Count; i++) 
			{
				Console.WriteLine (i);
				if (item == liPhoneBook[i].Item1) 
				{
					Console.WriteLine (liPhoneBook[i].Item2);
					iPosition = i+1;
					break;
				}
			}
		}
	}
}

Enjoy it! 🙂