[leetcode] 771. Jewels and Stones

 

You're given strings jewels representing the types of stones that are jewels, and stones representing the stones you have. Each character in stones is a type of stone you have. You want to know how many of the stones you have are also jewels.

Letters are case sensitive, so "a" is considered a different type of stone from "A".

 

Example 1:

Input: jewels = "aA", stones = "aAAbbbb"
Output: 3

Example 2:

Input: jewels = "z", stones = "ZZ"
Output: 0

 

Constraints:

• 1 <= jewels.length, stones.length <= 50
• jewels and stones consist of only English letters.
• All the characters of jewels are unique.

 

class Solution(object):
    def numJewelsInStones(self, jewels, stones):
        """
        :type jewels: str
        :type stones: str
        :rtype: int
        """
        freqs = {} 
        for char in stones:
            if char not in freqs:
                freqs[char] = 1 
            else:
                freqs[char] += 1 
        count = 0 
        for char in jewels:
            if char in freqs:
                count += freqs[char]

        return count

 

class Solution(object):
    def numJewelsInStones(self, jewels, stones):
        """
        :type jewels: str
        :type stones: str
        :rtype: int
        """
        freqs = collections.defaultdict(int)
        count = 0
        for char in stones:
            freqs[char] += 1  

        for char in jewels:
            count += freqs[char]

        return count

 

 

class Solution(object):
    def numJewelsInStones(self, jewels, stones):
        """
        :type jewels: str
        :type stones: str
        :rtype: int
        """
        freqs = collections.Counter(stones)
        count = 0
        for char in jewels:
            count += freqs[char]

        return count

 

class Solution(object):
    def numJewelsInStones(self, jewels, stones):
        """
        :type jewels: str
        :type stones: str
        :rtype: int
        """
        return sum([s in jewels for s in stones])