Here's a fairly efficient, but possibly not optimal, solution with some explanation.

```
public void MoveZeroes(int[] nums) {
/* The logic here is to iterate through the loop once while
* 1) keeping a count of the number of zeros, and
* 2) making sure that the array to the left of the current item is defragmented (contains no zeros).
* The number of zeros removed will be re-added to the end iteration.
*/
int noOfZeros = 0;
for (int i = 0; i < nums.Length; i++)
{
if (nums[i] == 0)
{
noOfZeros++;
continue;
}
// Assert(nums[i] != 0);
// Copy the current item to the degragmented array to the left of the current item.
nums[i - noOfZeros] = nums[i];
}
// Re-add the removed zeros.
for (int i = 0; i < noOfZeros; i++)
{
nums[nums.Length - 1 - i] = 0;
}
}
```