Question: I'm trying to find something equivalent to `remove_range` (which does not exist of course) as shown below. Seems there is no easy way to implement this functionality.

```
a = [0,2,8,2,4,5,]
b = a.remove_range(1,2) #remove items between index 1 and 2 ,inclusively
#expect b == [0,2,4,5]
b = a.remove_range(3,4)
#expect b == [0,2,8,5]

```

**Please test at least above two cases before posting your solution :)** 

Suppose the size of the range is M, this operation should requires O(1) space and O(N-M) time complexity.

EDIT:
I see people keep posting the `a - a[range]`. But it is not correct, that is to remove the elements exists in a[range], not to remove the the element belongs to range.

`a - a[1..2]` will return `[0, 4, 5]`. However,we want to keep the 3rd element which is `2`.

Answer: 
You can do some cool tricks with the Enumerable module:

```
a = [0, 2, 8, 2, 4, 5]
r = 1..2
a.reject.with_index { |v, i| r.include?(i) }  # => [0, 2, 4, 5]

```

Note that this does not modify the original array, but returns a new one. You can use `reject!` if you want to modify the array.
```
a = [0,2,8,2,4,5]    
j = 1

(3..4).each do |i|
    j == 1 ? a.delete_at(i) : a.delete_at(i-1)
    j += 1
end

b = a
[0, 2, 8, 5]

```