# Add an array with itself

## Python 3, ~~67~~ ~~65~~ 42 bytes

Uses the fact that the sum of an empty array is 0

```
lambda x,y:[sum(x[i::y])for i in range(y)]
```

Try it online!

## MATL, 4 bytes

```
e!Xs
```

Try it online!

First bit of MATL code I've written! Takes two inputs, `a`

as a row vector (comma-separated) and `l`

as a number. Works out to be

```
e # reshape `a` into `l` rows (auto pads with 0)
! # transpose
Xs # sum down the columns
```

## Jelly, ~~7~~ 6 bytes

1 byte thanks to Dennis.

```
;0$¡sS
```

Try it online!