题解 | #找出字符串中第一个只出现一次的字符#

import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        while (sc.hasNext()) {
            Map<Character, Integer> map = new LinkedHashMap<>();
            String line = sc.nextLine();
            for (int i = 0; i < line.length(); i++) {
                char c = line.charAt(i);
                map.put(c, map.getOrDefault(c, 0) + 1);
            }
            boolean flag = false;
            for (Map.Entry<Character, Integer> entry : map.entrySet()) {
                if (entry.getValue() == 1) {
                    System.out.println(entry.getKey());
                    flag = true;
                    break;
                }
            }
            if (!flag) {
                System.out.println(-1);
            }
        }
        sc.close();
    }
}