Gemstones

FRom hackerrank

John has collected various rocks. Each rock has various minerals embeded in it. Each type of mineral is designated by a lowercase letter in the range . There may be multiple occurrences of a mineral in a rock. A mineral is called a gemstone if it occurs at least once in each of the rocks in John's collection.

Given a list of minerals embedded in each of John's rocks, display the number of types of gemstones he has in his collection.

For example, the array of mineral composition strings . The minerals  and  appear in each composite, so there are  gemstones.

Solution in C# -

class Solution {

    static int gemstones(string[] arr) {

        string s = arr[0];

        int gems = 0;

        for(int i=0; i<s.Length; i++)

        {

            int count = 1;

            for(int j=1; j<arr.Length; j++)

            {

                if(arr[j].Contains(s[i]))

                {

                    count++;

                    int index = arr[j].IndexOf(s[i]);

                    arr[j] = arr[j].Substring(0,index)+arr[j].Substring(index+1);

                }

            }

            if(count>=arr.Length)

            gems++;

        }

        return gems;

    }

    static void Main(string[] args) {

        TextWriter textWriter = new StreamWriter(@System.Environment.GetEnvironmentVariable("OUTPUT_PATH"), true);

        int n = Convert.ToInt32(Console.ReadLine());

        string[] arr = new string [n];

        for (int i = 0; i < n; i++) {

            string arrItem = Console.ReadLine();

            arr[i] = arrItem;

        }

        int result = gemstones(arr);

        textWriter.WriteLine(result);

        textWriter.Flush();

        textWriter.Close();

    }

}