title: Train-3
Contest: lanqiao
tags: Contest
theme: 
date: 2025-04-11
author: 
- AllenYGY
publish: TrueTrain-3
int gcd(int a,int b){
	if (b==0) return a;
	else return gcd(b,a%b);	
}
string FJ_string(int n){
	if (n==1) return "A";
	else return FJ_string(n-1)+char(int('A') +(n-1))+ FJ_string(n-1);
}
从1~n这n个整数中随机选取任意多个,输出所有可能的选择方案。