Code example translated from Java to C

highestProductOf3.c

/* Code example translated from Java to C */

#include <stddef.h>

int minInt(int a, int b)
{
	return a < b ? a : b;
}

int maxInt(int a, int b)
{
	return a > b ? a : b;
}

int highestProductOf3(const int* arrayOfInts, size_t size) 
{
	size_t i;
	
	if (size < 3)
		return 0; /* indicate error */

	/* We're going to start at the 3rd item (at index 2)
	   so pre-populate highests and lowests based on the first 2 items.
	   we could also start these as null and check below if they're set
	   but this is arguably cleaner */
	int highest = maxInt(arrayOfInts[0], arrayOfInts[1]);
	int lowest  = minInt(arrayOfInts[0], arrayOfInts[1]);

	int highestProductOf2 = arrayOfInts[0] * arrayOfInts[1];
	int lowestProductOf2  = arrayOfInts[0] * arrayOfInts[1];

	/* except this one--we pre-populate it for the first /3/ items.
	   this means in our first pass it'll check against itself, which is fine. */
	int highestProductOf3 = arrayOfInts[0] * arrayOfInts[1] * arrayOfInts[2];

	/* walk through items, starting at index 2 */
	for (i = 2; i < size; i++) {
		int current = arrayOfInts[i];

		/* do we have a new highest product of 3?
		   it's either the current highest,
		   or the current times the highest product of two
		   or the current times the lowest product of two */
		highestProductOf3 = maxInt(maxInt(
			highestProductOf3,
			current * highestProductOf2),
			current * lowestProductOf2);

		/* do we have a new highest product of two? */
		highestProductOf2 = maxInt(maxInt(
			highestProductOf2,
			current * highest),
			current * lowest);

		/* do we have a new lowest product of two? */
		lowestProductOf2 = minInt(minInt(
			lowestProductOf2,
			current * highest),
			current * lowest);

		/* do we have a new highest? */
		highest = maxInt(highest, current);

		/* do we have a new lowest? */
		lowest = minInt(lowest, current);
	}

	return highestProductOf3;
}