HackerRank: Two strings - https://www.hackerrank.com/challenges/two-strings/submissions/code/18506948

TwoStrings.cs

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

namespace TwoStrings
{
    /*
     * HackerRank:
     * https://www.hackerrank.com/challenges/two-strings
     * 
     * 
     */
    class Program
    {
        static void Main(string[] args)
        {
            string s1 = Console.ReadLine();
            int n1 = Convert.ToInt16(s1);

            for (int i = 0; i < n1; i++)
            {
                string sA = Console.ReadLine();
                string sB = Console.ReadLine();

                if (hasACommonSubstring(sA, sB))
                    Console.WriteLine("YES"); 
                else
                    Console.WriteLine("NO"); 
            }
        }

        /*
         * s1.Length > 1, <=10^5
         */
        public static bool hasACommonSubstring(string s1, string s2)
        {
            bool[] A = getLatinArray(s1);
            bool[] B = getLatinArray(s2);
            
            for (int i = 0; i < 26; i++)
            {
                if (A[i] && B[i])
                    return true; 
            }

            return false; 
        }

        private static bool[] getLatinArray(string s1)
        {
            bool[] A = new bool[26];

            int count = 0; 
            foreach (char c in s1)
            {
                int index = c - 'a';
                if (A[index] != true)
                {
                    A[index] = true;
                    count++;
                }

                if(count == 26)
                    break; 
            }

            return A; 
        }
    }
}