Stones and Jewels

stones_n_jewels.py

""" You're given strings J representing the types of stones that are jewels, and S representing the stones you have.  Each character in S is a type of stone you have.  You want to know how many of the stones you have are also jewels.
    The letters in J are guaranteed distinct, and all characters in J and S are letters. Letters are case sensitive, so "a" is considered a different type of stone from "A".
    Example 1:
    Input: J = "aA", S = "aAAbbbb"
    Output: 3
    Example 2:
    Input: J = "z", S = "ZZ"
    Output: 0
    Note:
      • S and J will consist of letters and have length at most 50.
      • The characters in J are distinct.
      
"""

def numJewelsInStones(J, S):
    j = list(J)
    s = list(S)
    counts = 0

    for _j in j:
        for _s in s:
            if _j == _s:
                counts += 1
    return counts