Leetcode 128 - longest consecutive sequence - using SortedSet

Leetcode128_LongestConsecutiveSequence_practice.cs

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

namespace Leetcode128_LongestConsecutiveSequence_FirstTime
{
    /// <summary>
    /// code review on June 29, 2017
    /// https://leetcode.com/problems/longest-consecutive-sequence/#/description
    /// </summary>
    class Leetcode128_LongestConsecutiveSequence_FirstTime
    {
        static void Main(string[] args)
        {
        }

        /// <summary>
        /// code review on June 29, 2017
        /// Sort those numbers using binary search tree
        /// </summary>
        /// <param name="nums"></param>
        /// <returns></returns>
        public int LongestConsecutive(int[] nums)
        {
            if (nums == null || nums.Length == 0)
            {
                return 0; 
            }

            var binarySearchTree = new SortedSet<int>(nums);

            int maxSequence     = 1;
            int currentSequence = 1;

            int lastNumber = int.MaxValue;

            foreach (var number in binarySearchTree)
            {
                if (lastNumber != int.MaxValue && number == lastNumber + 1)
                {
                    currentSequence++;
                }
                else
                {
                    currentSequence = 1;
                }

                maxSequence     = Math.Max(maxSequence, currentSequence);
                lastNumber = number;
            }

            return maxSequence;
        }
    }
}