old_contents: # Time:  O(m + n)
  # Space: O(n)
  
  class Solution(object):
      def numJewelsInStones(self, J, S):
          """
          :type J: str
          :type S: str
          :rtype: int
          """
          lookup = set(J)
          return sum(s in lookup for s in S)
          
  
new_contents: # Time:  O(m + n)
  # Space: O(n)
  
  # 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.
  
  class Solution(object):
      def numJewelsInStones(self, J, S):
          """
          :type J: str
          :type S: str
          :rtype: int
          """
          lookup = set(J)
          return sum(s in lookup for s in S)
          
  
subject: Update jewels-and-stones.py