Hanoi塔问题（递归）

#include<iostream>
#include<cstdio>
using namespace std;
int sum;
int f(int n,char a,char b,char c){

    if(n == 1){printf("1 from a to b\n");sum++;return sum;}
    else {
        f(n-1,a,c,b);
        printf("%d from %c to %c\n",n,a,c);sum++;
        f(n-1,b,a,c);
    }
}
int main(){
    int cases,  n;
    cin>>cases;
    while(cases--){
        cin>>n;
        sum = 0;
        f(n,'a','b','c');
        printf("sum = %d\n",sum);
    }
    return 0;
}