why is my 3n+1 problem solution wrong?
- by nunos
I have recently started reading "Programming Challenges" book by S. Skiena and believe or not I am kind of stuck in the very first problem.
Here's a link to the problem: 3n+1 problem
Here's my code:
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
unsigned long calc(unsigned long n);
int main()
{
int i, j, a, b, m;
vector<int> temp;
while (true)
{
cin >> i >> j;
if (cin.fail())
break;
if (i < j)
{
a = i;
b = j;
}
else
{
a = j;
b = i;
}
temp.clear();
for (unsigned int k = a; k != b; k++)
{
temp.push_back(calc(k));
}
m = *max_element(temp.begin(), temp.end());
cout << i << ' ' << j << ' ' << m << endl;
}
}
unsigned long calc(unsigned long n)
{
unsigned long ret = 1;
while (n != 1)
{
if (n % 2 == 0)
n = n/2;
else
n = 3*n + 1;
ret++;
}
return ret;
}
I know the code is inefficient and I should not be using vectors to store the data. Anyway, I still would like to know what it's wrong with this, since, for me, it makes perfect sense, even though I am getting WA (wrong answer at programming challenges judge and RE (Runtime Error) at UVa judge).
Thanks.
