Gemstones.py

#!/bin/python3

import math
import os
import random
import re
import sys

#
# Complete the 'gemstones' function below.
#
# The function is expected to return an INTEGER.
# The function accepts STRING_ARRAY arr as parameter.
#

def gemstones(arr):
    # Write your code here
    # Create a list of sets representing minerals in each rock
    mineral_sets = [set(rock) for rock in arr]

    # Take the intersection of all sets
    gemstones_set = set.intersection(*mineral_sets)

    # Return the number of gemstones
    return len(gemstones_set)

if __name__ == '__main__':
    fptr = open(os.environ['OUTPUT_PATH'], 'w')

    n = int(input().strip())

    arr = []

    for _ in range(n):
        arr_item = input()
        arr.append(arr_item)

    result = gemstones(arr)

    fptr.write(str(result) + '\n')

    fptr.close()