/*  Create a function that goes through the array, incrementing 
 *  (+1) for each odd number and decrementing (-1) 
 *  for each even number.
 *  ex. transform([1, 2, 3, 4, 5]) ➞ [2, 1, 4, 3, 6]
 */
std::vector<int> transform(std::vector<int> arr) {
	for(int i = 0;i<arr.size();i++){
		//  evaluate if even, -1 if even
		if(arr[i]%2 == 0){arr[i]-=1;}
		//  evaluate if odd, +1 if odd
		else arr[i]+=1;
	}
	return arr;
}