Dennis Ritchie, Father of C and Co-Developer of Unix, Dies

POST: http://www.wired.com/wiredenterprise/2011/10/dennis-ritchie/

My first learned programming language is C language.

My first C language program:

//"@begin_of_source_code"
/*   @JUDGE_ID:   7382YR   100   C++  */

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>

/**** <<<<<<<<<<<<<< The 3n+1 problem >>>>>>>>>>>>>> ****
 * Purpose: see follows sub-function description        *
 ********************************************************/

unsigned long _max(unsigned long p, unsigned long q);
unsigned long lenght(unsigned long n, unsigned long cycle_lenght);
void swap(unsigned long *a, unsigned long *b);

int main(void)
{

        unsigned long i, j; // input - the maximum cycle lenght of i to j

#ifndef ONLINE_JUDGE
        close (0); open ("myprog.in", O_RDONLY);
        close (1); open ("myprog.out", O_WRONLY | O_CREAT, 0600);
#endif

        scanf("%d%d", &i, &j);

        if (i > j) { swap(i, j); } // check if i <= j

        printf("%d %d %d\n", i, j, _max(i, j));

        return (0);
}

/*******************************************************
 * _max -- to get maximum cycle lenght between p and q *
 *    p -- lower bound                                 *
 *    q -- upper bound                                 *
 *                                                     *
 * Return                                              *
 *  max -- asked                                       *
 *******************************************************/
unsigned long _max(unsigned long p, unsigned long q)
{
        unsigned long max = 1; // maximum cycle lenght. start with 1.

        for (unsigned long ctr = p; ctr < q+1; ctr++) // ctr - counter.
        {
                if(lenght(ctr,0) > max)
                {
                        max = lenght(ctr,0);
                }
        }
        return max;
}

/*******************************************************
 * lenght -- to get the cycle lenght of a number n     *
 *                                                     *
 *      n -- that number                               *
 *   temp -- to store current lenght (for recusion)    *
 *                                                     *
 * Return                                              *
 *   temp. if n == 1, or continue                      *
 *******************************************************/
unsigned long lenght(unsigned long n, unsigned long temp)
{
        temp++;
        if (n == 1)
                return temp;
        else
        {
                if (n % 2 == 0)
                        n = n / 2;
                else
                        n = 3 * n + 1;

                return lenght(n, temp);
        }
}

void swap(unsigned long *a, unsigned long *b)
{
        *a = *a + *b;
        *b = *a - *b;
        *a = *a - *b;
}
//"@end_of_source_code"

Really ugly.