思路

这一道题的关键就是去重。

思路如下:

  1. 将字符串变成字符数组;
  2. 遍历数组,将元素插入Set中;
  3. 统计Set的size

代码实现

import java.util.*;

public class Main {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        while (scanner.hasNext()) {
            String str = scanner.next();
            char[] chars = str.toCharArray();
            Set<Character> set = new HashSet<>();
            for (char aChar : chars) {
                set.add(aChar);
            }
            System.out.println(set.size());
        }
    }
}