# find-even-index

You are going to be given an array of integers. Your job is to take that array and find an index N where the sum of the integers to the left of N is equal to the sum of the integers to the right of N. If there is no index that would make this happen, return `-1`.

### For example:

Let's say you are given the array `{1,2,3,4,3,2,1}`:
Your function will return the index `3`, because at the 3rd position of the array, the sum of left side of the index (`{1,2,3}`) and the sum of the right side of the index (`{3,2,1}`) both equal `6`.

Let's look at another one.
You are given the array `{1,100,50,-51,1,1}`:
Your function will return the index 1, because at the 1st position of the array, the sum of left side of the index (`{1}`) and the sum of the right side of the index (`{50,-51,1,1}`) both equal `1`.

### Last one:

You are given the array `{20,10,-80,10,10,15,35}`
At index `0` the left side is `{}`
The right side is `{10,-80,10,10,15,35}`
They both are equal to 0 when added. (Empty arrays are equal to 0 in this problem)
Index `0` is the place where the left side and right side are equal.

**Note:** Please remember that in most programming/scripting languages the index of an array starts at `0`.

### Input:

An integer array of length `0 < arr < 1000`. The numbers in the array can be any integer positive or negative.

### Output:

The lowest index N where the side to the left of N is equal to the side to the right of N. If you do not find an index that fits these rules, then you will return `-1`.

**Note:**

If you are given an array with multiple answers, return the lowest correct index.

## Install

```
$ npm install @abranhe/codewars
```

## Usage

```js
const codewars = require('@abranhe/codewars');

codewars.findEvenIndex([1, 2, 3, 4, 3, 2, 1]);
//=> 3
```

## API

### codewars.findEvenIndex(input)

#### input

Type: `array`