# (YKL08(UVA100)) The 3n + 1 problem :
YKL08_UVA100_The_3n_1_problem.cpp
```cpp=
#include <iostream>
using namespace std;
int main()
{
int n, m;
while (cin >> n >> m)
{
// 先輸出免得被換掉
printf("%d %d ",n,m);
// n要比較小
if (n>m)
{
swap(n,m);
}
// 嘗試n到m的所有數字
int c = 1,max_c=0;
for (int i = n; i < m+1; i++)
{
int a=i,c=1;
while (a != 1)
{
if (a % 2 == 0)
{
a /= 2;
}
else
{
a = 3 * a + 1;
}
c++;
}
if (c>max_c)
{
max_c=c;
}
}
// out
printf("%d\n", max_c);
}
}
```

