Computer Programming Contest Preparation

    1 /*@JUDGE_ID:   110101   100 C "3n+1"*/
    2 
    3 #include <stdio.h>
    4 
    5 unsigned long int func(unsigned long int num);
    6 void swap(unsigned long int *tx,unsigned long int *ty);
    7 
    8 int main(void)
    9 {
   10     unsigned long x,y,z,max=0,temp;
   11     int flag;
   12     fflush(stdout);
   13     while (scanf("%lu %lu", &x,&y)==2)
   14         {
   15             flag = 0;
   16             if (x>y)
   17                 {
   18                     swap(&x,&y);
   19                     flag =1;
   20                 }
   21             max = 0;
   22             for (z=x; z<=y; z++)
   23                 {
   24                     temp = func(z);
   25                     if (temp>max) max = temp;
   26                 }
   27             if (!flag)
   28                 printf("%lu %lu %lu\n",x,y,max);
   29             else
   30                 printf("%lu %lu %lu\n",y,x,max);
   31         }
   32     return 0;
   33 }
   34 
   35 void swap(unsigned long int *tx,unsigned long int *ty)
   36 {
   37     unsigned long int temp;
   38     temp = *tx;
   39     *tx = *ty;
   40     *ty = temp;
   41 }
   42 unsigned long int func(unsigned long int num)
   43 {
   44     if (num == 1)
   45         {
   46             return 1;
   47         }
   48     else if (num%2==0)
   49         {
   50             return 1 + func(num/2);
   51         }
   52     else
   53         {
   54             return 1 + func(num*3+1);
   55         }
   56 }
   57