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// @Title: 第一个只出现一次的字符 (第一个只出现一次的字符  LCOF)
// @Author: 15816537946@163.com
// @Date: 2022-02-10 00:20:18
// @Runtime: 0 ms
// @Memory: 2.2 MB

impl Solution {
    pub fn first_uniq_char(s: String) -> char {
        let mut vec = vec![0; 26];
        for c in s.chars() {
            let i = (c as u8 - 'a' as u8) as usize;
            vec[i] += 1;
        }

        for c in s.chars() {
            let i = (c as u8 - 'a' as u8) as usize;
            if vec[i] == 1 {
                return c;
            }
        }
        ' '
    }
}