1160. Find Words That Can Be Formed by Characters*

1160. Find Words That Can Be Formed by Characters*

https://leetcode.com/problems/find-words-that-can-be-formed-by-characters/

题目描述

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

C++ 实现 1

统计 chars 中每个字符的个数, 判断 words 中的每个 string 是否可以使用 chars 中的字符生成.

class Solution {
private:
	// 注意这里的 nums 不是引用, 会发生数据的拷贝, 从而不影响 records 数组
    bool isGood(vector<int> nums, const string &str) {
        for (auto &c : str) {
            if (nums[c - 'a'] == 0) return false;
            else nums[c - 'a'] --;
        }
        return true;
    }
public:
    int countCharacters(vector<string>& words, string chars) {
        vector<int> records(26, 0);
        int res = 0;
        for (auto &c : chars) records[c - 'a'] ++;
        for (auto &s : words)
            if (isGood(records, s))
                res += s.size();
        return res;
    }
};