[LeetCode]#771. Jewels and Stones

Environment: Python 3.7

Key technique: count

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.

Analysis:

Use count function to get number of J in S as below.

Solution:

class Solution:
    def numJewelsInStones(self, J, S):
        j_n=0
        for j in J:
            j_n=j_n+S.count(j)
        return j_n

Submitted result: