#include<iostream>
using namespace std;
int main()
{
int i,j;
cin>>i>>j;
int max=0;
for(int t=i;t<=j;t++){
int len=1;
int a=t;
len ++;
while(a!=1){
if(a%2==0){
a=a/2;
}
else{
a=3*a+1;
}
++len;
}
if(len>max) max=len;
}
cout<<max<<endl;
return 0;
}
原文:http://www.cnblogs.com/sysu-eeman-yang/p/5987455.html