// Alex Launi
// Assignment 1
// 1/23/2009
//
// EMAIL THIS TOO  c21070100@lucas.cis.temple.edu

#include <stdio.h>

#define SIZE 10

void evenOnLeft(int[], int);
void printA(int[], int);
void reverse(int[], int);
float average(int[], int);
int* copy_array(int[], int);

int main(int argc, char **argv)
{
  int A[] = {9, 21, 321, 117, 27, 64, 13, 9, 12, 208};
  printA(A, SIZE);

  printf("The average of A[] is %f\n", average(A,SIZE));

  reverse(A, SIZE);
  printA(A, SIZE);

  evenOnLeft(A, SIZE);
  printA(A, SIZE);

  return 0;
}

/* prints A[] inside parentheses with each value separated
   by commas to stdout */
void printA(int A[], int length)
{
	int i;

	printf("(");
	for(i = 0; i < length; i++) {
		if (i != length - 1)
			printf("%d, ", A[i]);
		else
			printf("%d", A[i]);
	}
	printf(")\n");
}

/* returns the average of the items in A[] or 0.0 if A is empty */
float average(int A[], int length)
{
	int i;
	int sum = 0.0;

	if (length < 1) return 0.0;

	for (i = 0; i < length; i++) {
		sum += A[i];
	}

	return (float) sum/length;
}

/* Reverses the values in A[].  For example, if before the function,
   A[] contained [1,2,3,4,5], after the function, A[] contains
   [5,4,3,2,1] */
void reverse(int A[], int length)
{
	int i, j;
	int* B;

	B = copy_array(A, length);
	for (i = length - 1, j = 0 ; i >= 0 && j < length; i--) {
		A[j] = B[i];
		j++;
	}
}

/* Moves all of the even integers in A to the left hand side of A
   and the odd integers to the right hand side

   For example, if before the function, A[] contained [1,2,3,4,5],
   after the function A[] could contain [2,4,1,3,5] */
void evenOnLeft(int A[], int length)
{
	int* B;
	int i1 = 0, i2 = length, j = 0;

	if (length < 1) return;

	B = copy_array(A, length);
	while (j < length) {
		if (B[j] % 2 == 0) {
			A[i1] = B[j];
			i1++;
		}
		else {
			A[i2] = B[j];
			i2--;
		}
		j++;
	}
}

// FIXME, there has got to be a better way
int* copy_array(int A[], int length)
{
	int i;
	int* B;
	for (i = 0; i < length; i++) {
		B[i] = A[i];
	}

	return B;
}