题解 | #字符个数统计#

import java.util.Scanner;

// 注意类名必须为 Main, 不要有任何 package xxx 信息
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int[] list = new int[128];
        String s = in.nextLine();
        for (int j = 0; j < s.length(); j++) {
            byte b = s.getBytes()[j];
            // 将字符转化为ASCII码
            int i = (int)b;
            list[i] = 1;
        }
        int count = 0;
        for (int i = 0; i < list.length; i++) {
            if (list[i] == 1) {
                count++;
            }
        }
        System.out.println(count);
    }
}