题解 | #字符个数统计#

数组 s1[str.charAt(i)]

import java.util.*;

public class Main{
    public static int[] s1 = new int[128];
    public static void main(String[] args){
        Scanner in =  new Scanner(System.in);
        String str = in.nextLine();
        int sum = 0;
        
        for(int i=0; i < str.length(); i++){
            s1[str.charAt(i)]++;
        }
        for(int i=0; i < 128; i++){
            if(s1[i] != 0){
                sum++;
            }
        }
        System.out.println(sum);
        
    }
}