exercism/c/collatz-conjecture/collatz_conjecture.c

#include "collatz_conjecture.h"

int steps(int start) {

  if (start < 1) {
    return ERROR_VALUE;
  }

  int count = 0;

  while (start != 1) {

    if (start % 2 == 0) {
      start /= 2;
    } else {
      start = start * 3 + 1;
    }

    count++;
  }

  return count;
}