O(N) Time (Sum - O(N), for loop - O(N) - > O(2N) = O(N))

O(1) Space

```
public int[] ProductOfArrayExceptSelf(int[] nums)
{
int current;
int sum = nums.Sum();
for (int i = 0; i < nums.Length; i++)
{
current = nums[i];
nums[i] = sum - current;
}
return nums;
}
```