Project Euler Question 14 (Collatz Problem)

Question

The following iterative sequence is defined for the set of positive integers:

n ->n/2 (n is even) n ->3n + 1 (n is odd)

Using the rule above and starting wit

Answer 1

Fixing the unsigned int issue in the original question.

Added array for storing pre-computed values.

include                                                                                                                                      
#define LIMIT 1000000

unsigned int dp_array[LIMIT+1];

unsigned int iteration(unsigned int value)
{
 if(value%2==0)
  return (value/2);
 else
  return (3*value+1);
}

unsigned int count_iterations(unsigned int value)
{
 int count=1;
 while(value!=1)
 {
 if ((value<=LIMIT) && (dp_array[value]!=0)){
   count+= (dp_array[value] -1);
   break;
  } else {
   value=iteration(value);
   count++;
  }
 }
 return count;
}

int main()
{
 int iteration_count=0, max=0;
 int i,count;
 for(i=0;i<=LIMIT;i++){
  dp_array[i]=0;
 }

 for (i=1; imax)
   {
   max=iteration_count;
   count=i;
   }
//  printf(" %d \n", max);

 }

 printf("Count = %d\ni = %d\n",max,count);

}

o/p: Count = 525 i = 837799