[leetcode]first-unique-character-in-a-string 字符串中的第一个唯一字符

. - 力扣（LeetCode）

class Solution {
public:int firstUniqChar(string s) {unordered_map<int, int> frequency;for (char ch: s) {++frequency[ch];}for (int i = 0; i < s.size(); ++i) {if (frequency[s[i]] == 1) {return i;}}return -1;}
};