【leetcode】1160. Find Words That Can Be Formed by Characters

题目如下：

You are given an array of strings words and a string chars.

A string is good if it can be formed by characters from chars (each character can only be used once).

Return the sum of lengths of all good strings in words.

Example 1:

Input: words = ["cat","bt","hat","tree"], chars = "atach"
Output: 6
Explanation: 
The strings that can be formed are "cat" and "hat" so the answer is 3 + 3 = 6.

Example 2:

Input: words = ["hello","world","leetcode"], chars = "welldonehoneyr"
Output: 10
Explanation: 
The strings that can be formed are "hello" and "world" so the answer is 5 + 5 = 10.

Note:

1. 1 <= words.length <= 1000
2. 1 <= words[i].length, chars.length <= 100
3. All strings contain lowercase English letters only.

解题思路：很简单的题目，chars中每个字符出现的次数要大于等于word中每个字符出现的次数，即表示可以组成这个word。

代码如下：

class Solution(object):
    def countCharacters(self, words, chars):
        """
        :type words: List[str]
        :type chars: str
        :rtype: int
        """
        res = 0
        for word in words:
            flag = True
            for i in word:
                if word.count(i) > chars.count(i):
                    flag = False
                    break
            if flag: res += len(word)
        return res