Leetcode ​​面试题 01.01. 判定字符是否唯一​​

class Solution {
public:
    bool isUnique(string astr) {
        int lowerLetters[26] = { 0 };
        for (char& ch : astr)
        {
            int ret = ch - 'a';
            ++lowerLetters[ret];
        }
        for (int i = 0; i < 26; i++)
        {
            if (lowerLetters[i] > 1)
            {
                return false;
            }
        }
        return true;
    }
};