HackerRank: String algorithm - Anagram - https://www.hackerrank.com/challenges/anagram

Anagram.cs

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

namespace Anagram
{
    class Program
    {
        /*
         * https://www.hackerrank.com/challenges/anagram
         * 
         */
        static void Main(string[] args)
        {
            string s1 = Console.ReadLine();

            int n = Convert.ToInt16(s1); 
            for(int i=0;i<n;i++)
            {
                string s = Console.ReadLine();
                Console.WriteLine(getMinNumberToChange(s)); 
            }
        }

        /*
         * len(s1) + len(s2) >=1, and <= 10000
         * 1 <= T <= 100
         * 
         * string will contain only characters from a to z
         */
        public static int getMinNumberToChange(string s)
        {
            if (s == null || s.Length == 0)
                return -1; 
            int n = s.Length;
            if (n % 2 == 1)
                return -1;           

            int SIZE = 26;

            int count = 0;
            int[] sumA = getSumArray(s, 0, n/2-1);
            int[] sumB = getSumArray(s, n/2, n-1);

            for (int i = 0; i < SIZE; i++)
            {
                if (sumA[i] > 0)
                    // add count of chars in array sumA but not in sumB
                    count += (sumA[i] >= sumB[i]) ? (sumA[i] - sumB[i]) : 0;   // axxbbbxx, axxb, a 1, b 1, x 2; bbxx, a 0, b 2, x 2 
            }

            return count;
        }

        public static int[] getSumArray(string s1, int start, int end)
        {
            int SIZE = 26;
            int[] sumA = new int[SIZE];

            for (int i = start; i <= end; i++ )
            {
                sumA[s1[i] - 'a']++;
            }

            return sumA;
        }        
    }
}