(需复习)LeetCode--1002.查找共用字符（C++描述）

// Source : https://leetcode-cn.com/problems/find-common-characters/
// Date : 2022-1-25

class Solution {
public:
    vector commonChars(vector& words) {
        vector minfreq(26, INT_MAX);
        vector freq(26);
        for (const string& word: words) 
        {
            //因为涉及到自增的问题，因此这里必须给数组填充0
             fill(freq.begin(), freq.end(), 0);
            //将每个单词的出现次数放入数组中,下标从0--25
            for (char ch: word) 
                ++freq[ch - 'a'];
            for (int i = 0; i < 26; ++i) 
                //从index入手，将最小的赋值
                minfreq[i] = min(minfreq[i], freq[i]);
        }
        vector ans;
        for (int i = 0; i < 26; ++i) {
            for (int j = 0; j < minfreq[i]; ++j) {
                //如果一个元素出现多次，则需要把这个元素都添加进结果数组，注意：从Index转换到字符的方式
                ans.emplace_back(1, i + 'a');
            }
        }
        return ans;
    }
};