3Sum 2 Different implementations complexity

These are 2 implementations for the http://en.wikipedia.org/wiki/3SUM problem,
The first one is mine.
and in the second one I implemented Wiki's pseudo code.

Can someone please tell me if there is a difference between the two in complexity of runtime and memory space?

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

namespace ConsoleApplication2
{

    //the 3SUM problem asks if a given set of n integers, 
    //each with absolute value bounded by some polynomial in n, contains three elements that sum to zero
    public class ThreeSum
    {
        public ThreeSum()
        {
            List<int> array = new List<int> { 25, -10, -7, -3, 2, 4, 8, 10 };
            List<int> res = SolveThreeSum(array);
            res = SolveThreeSumWiki(array);
        }

        public List<int> SolveThreeSum(List<int> array)
        {
            for (int i = 0; i < array.Count - 2; i++ )
            {
                for (int j = i + 1; j < array.Count -1; j++)
                {
                    for (int k = i + 2; k < array.Count ; k++)
                    {
                        if ((array[i] + array[j] + array[k]) == 0)
                        {
                            return new List<int> { array[i], array[j], array[k] };
                        }   
                    }                    
                }
            }
            return null;
        }

        public List<int> SolveThreeSumWiki(List<int> array)
        {
            array.Sort();
            for (int i = 0; i < array.Count - 3; i++)
            {
                int a = array[0];
                int start = i + 1;
                int end = array.Count - 1;
                while (start < end)
                {
                    int b = array[start];
                    int c = array[end];
                    if ((a + b + c) == 0)
                    {
                        return new List<int> { a, b, c };
                    }                    
                    else if (a+b+c > 0)
                    {
                        end = end - 1;
                    }
                    else
                    {
                         start = start + 1;
                    }
                }
            }
            return null;
        }
    }
}