Kindergarten adventure - HackerRank - study code C - score 30 (maximum score 30)

kindergartenAdventure_studycodeC.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.IO;
using System.Diagnostics;

namespace ProblemSolver
{
    struct Student
    {
        public int Res
        {
            private set;
            get;
        }

        public int Pos
        {
            private set;
            get;
        }

        public Student(int res, int pos)
        {
            Res = res;
            Pos = pos;
        }
    }

    class StudentComparer : IComparer<Student>
    {
        public int Compare(Student x, Student y)
        {
            int ret = x.Res.CompareTo(y.Res);
            if (ret == 0)
            {
                return x.Pos.CompareTo(y.Pos);
            }
            else
            {
                return ret;
            }
        }
    }


    class Solution
    {
        static char[] splitors = { ' ' };

        /* Input data here */
        static int n;
        static int[] t;
        static int[] r;                     

        static void Input()
        {
            n = int.Parse(Console.ReadLine());
            t = new int[n];
            r = new int[n];
            string[] str = Console.ReadLine().Split(splitors);
            for (int i = 0; i < n; i++)
            {
                t[i] = int.Parse(str[i]);
                r[i] = i - t[i];
            }
        }

        static void Search()
        {
            SortedSet<Student> s = new SortedSet<Student>(new StudentComparer());
            for (int i = 0; i < n; i++)
                if (r[i] >= 0)
                {
                    s.Add(new Student(r[i], i));
                }
            int ret = s.Count;
            int retval = 0;

            for (int i = 1; i < n; i++)
            {
                while (s.Count > 0)
                {
                    Student minS = s.Min;
                    if (minS.Res < i)
                    {
                        s.Remove(minS);
                    }
                    else
                    {
                        break;
                    }
                }
                if (n - 1 - t[i - 1] >= 0)
                {
                    s.Add(new Student(n - 1 - t[i - 1] + i, i));
                }

                if (s.Count > ret)
                {
                    ret = s.Count;
                    retval = i;
                }
            }

            Console.WriteLine(retval + 1);
        }

        static void Main(string[] args)
        {
            Input();
            Search();
        }
    }
}