Find Second largest number in array at most n+log₂(n)−2 comparisons [closed]

Answer 1

public static int FindSecondLargest(int[] input)
        {
            Dictionary> dictWinnerLoser = new Dictionary>();//Keeps track of loosers with winners
            List lstWinners = null;
            List lstLoosers = null;

            int winner = 0;
            int looser = 0;

            while (input.Count() > 1)//Runs till we get max in the array
            {
                lstWinners = new List();//Keeps track of winners of each run, as we have to run with winners of each run till we get one winner

                for (int i = 0; i < input.Count() - 1; i += 2)
                {
                    if (input[i] > input[i + 1])
                    {
                        winner = input[i];
                        looser = input[i + 1];
                    }
                    else
                    {
                        winner = input[i + 1];
                        looser = input[i];
                    }

                    lstWinners.Add(winner);


                    if (!dictWinnerLoser.ContainsKey(winner))
                    {
                        lstLoosers = new List();
                        lstLoosers.Add(looser);
                        dictWinnerLoser.Add(winner, lstLoosers);
                    }
                    else
                    {
                        lstLoosers = dictWinnerLoser[winner];
                        lstLoosers.Add(looser);
                        dictWinnerLoser[winner] = lstLoosers;
                    }
                }

                input = lstWinners.ToArray();//run the loop again with winners
            }

            List loosersOfWinner = dictWinnerLoser[input[0]];//Gives all the elemetns who lost to max element of array, input array now has only one element which is actually the max of the array

            winner = 0;

            for (int i = 0; i < loosersOfWinner.Count(); i++)//Now max in the lossers of winner will give second largest
            {
                if (winner < loosersOfWinner[i])
                {
                    winner = loosersOfWinner[i];
                }
            }

            return winner;
        }