【LeetCode】1002. Find common characters (C++)

1 topic description

Given a string array A consisting of only lowercase letters, return a list of all characters (including repeated characters) displayed in each string in the list. For example, if a character appears 3 times in each string, but not 4 times, you need to include the character 3 times in the final answer.
You can return the answers in any order.

2 Example description

2.1 Example 1

Input: ["bella","label","roller"]
Output: ["e","l","l"]

2.2 Example 2

Input: ["cool","lock","cook"]
Output: ["c","o"]

3 Problem solving tips

1 <= A.length <= 100
1 <= A[i].length <= 100
A[i][j] are lowercase letters

4 Detailed source code (C++)

class Solution {
    
    
public:
    vector<string> commonChars(vector<string>& A) {
    
    
        int arr[101][26] = {
    
     0 }; //全部初始化为0
        vector<string> res ; //返回值
        for ( int i = 0 ; i < A.size() ; i ++ )
        {
    
    
            for ( int j = 0 ; j < A[i].size() ; j ++ )
            {
    
    
                arr[i][A[i][j] - 'a'] ++ ; //计算每个字母出现的频率，并存入对应的下标
            }
        }

        for ( int i = 0 ; i < 26 ; i ++ )
        {
    
    
            int maxCount = INT_MAX ;
            for ( int j = 0 ; j < A.size() ; j ++ )
            {
    
    
                //分别计算26个字母在每个字符串中出现的频率，取最小的那个
                maxCount = min( maxCount , arr[j][i] );
            }

            char c = i + 'a' ;
            char buffer[2] = {
    
    c} ;
            while(maxCount--)
            {
    
    
                res.push_back(buffer);
            }
        }
        return res;
    }
};