#include<bits/stdc++.h>
using namespace std;
int n;
char a, b, c;
void f(int n, char a, char b, char c) {
	if (n == 1) {
		cout << a << "->" << n << "->" << b << endl;
		return;
	}
	f(n - 1, a, c, b); //将n-1个盘子从a移动到c(借助b)
	cout << a << "->" << n << "->" << b << endl;
	f(n - 1, c, b, a); //将n-1个盘子从c移动到b(借助a)
}
int main() {
	cin >> n >> a >> b >> c;
	//将n个盘子从a移动到b（借助c）
	f(n, a, b, c);
	return 0;
}

这是错的

using namespace std;
int n;
void DFS(int x, int from, int to) {
	if (x == 1) {
		cout << 'A' + from - 1 << 'A' + to - 1;
		return;
	}
	int as = 6 - from - to;
	DFS(x - 1, from, as);
	DFS(1, from, to);
	DFS(x - 1, as, to);
	return;
}
int main() {
	scanf("%d", &n);
	DFS(n, 1, 3);
	return 0;
}

a -> n-1 -> c a -> n -> b c -> n-1 -> b

递归