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***drdebcol*** · 08-02-2009, 10:38 PM

I was looking through some of problems that i used to solve few years ago, and i came across an simple problem !
Consider the following algorithm to generate a sequence of numbers. Start with an integer n. If n is even, divide by 2. If n is odd, multiply by 3 and add 1. Repeat this process with the new value of n, terminating when n = 1. For example, the following sequence of numbers will be generated for n = 22:

Code:

22 11 34 17 52 26 13 40 20 10 5 16 8 4 2 1

It is conjectured (but not yet proven) that this algorithm will terminate at n = 1 for every integer n. Still, the conjecture holds for all integers up to at least 1, 000, 000. For an input n, the cycle-length of n is the number of numbers generated up to and including the 1. In the example above, the cycle length of 22 is 16. So you need to find a number or cycle length !
This is solution is TPW :

Code:

program three_x_plus_one;

uses wincrt;

var

n,i:longint;

begin

 writeln('Enter number !');

 readln(n);

 i:=1;

 repeat

  begin

    if n mod 2 = 0 then

     n:=n div 2

     else

     n:=3*n+1;

     i:=i+1;

  end;

 until n=1;

 writeln('Solution is ',i);

end.

And for C++ coders :

Code:

# include <iostream>

# include <cstdio>

using namespace std;

int main()

{

    int i,n;

    cout<<"Enter number \n";

    cin>>n;

    i=1;

    while (n > 1)

    {

        if (n % 2 == 0)

         n=n/2;

         else

         n=3*n+1;

         i++;  

    }

    cout<<"Solution is "<<i<<"\n";\

    system("pause");

}