题解 | #字符个数统计#

int main()
{
    char c=0;
    int count[128]={0};
    int num=0;
    while((c=getchar())!='\n'){
        if(count[(int)(c)]==0){
            count[(int)(c)]=1;
            num++;
        }
    }
    printf("%d",num);
    return 0;
}