不用递归也能做

#include<stdio.h>
#define Main signed
#define int long long

Main main(){
    int n;
    scanf("%lld",&n);
    printf("%lld",n);
    while (n!=1){
        if (n%2==1){
            printf("->%lld",3*n+1);
            n=3*n+1;
        }else{
            printf("->%lld",n/2);
            n/=2;
        }
    }
    return 0;
}