Gems and stones python

Author: 18th CYL

Date: 2020-10-2

Tag: match count leetcode brute force solution

Title description:

The given string J represents the type of gem in the stone, and the string S represents the stone you own. Each character in S represents a type of stone you own, and you want to know how many of the stones you own are gems.

The letters in J are not repeated, and all the characters in J and S are letters. Letters are case sensitive, so "a" and "A" are different types of stones.

Example:

Example 1:

Input: J = "aA", S = "aAAbbbb"
Output: 3
Example 2:

Input: J = "z", S = "ZZ"
Output: 0

note:

S and J can contain up to 50 letters.
The characters in J are not repeated.

Problem solving ideas

1. Count the number of stones in each hand
2. It will be the sum of gems

Code

class Solution(object):
    def numJewelsInStones(self, J, S):
        """
        :type J: str
        :type S: str
        :rtype: int
        """
        if S == "":
            return 0
        num = 0    #宝石的数量
        S_dict = {} #各个元素数量
        for key in S:
            S_dict[key] = S_dict.get(key,0) + 1
        
        # print(S_dict.keys())
        for i in list(J):
            if i in S_dict.keys():
                num += S_dict[i]
        
        return num