Equal Sides Of An Array

Description:

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.

 

 

Solution:

1. Get indexes in order through for.
2. Based on the index, the left array and the right array are added respectively.
3. Checks whether the added values ​​are equal, and if they are equal, the corresponding index is returned.
4. If the same value is not found, -1 is returned.

 

 

JS code ::

function findEvenIndex(arr){
  for (let i=0;i<arr.length;i++) {
    let sum_left_item = 0
    let sum_right_item = 0

    for (let item of arr.slice(0,i)){
      sum_left_item += item
    }
    for (let item of arr.slice(i+1,)){
      sum_right_item += item
    }
    if (sum_left_item == sum_right_item){
      return i
    }
  }
  return -1
}

 

 

 

Python code ::

def find_even_index(arr):
    for i in range(len(arr)):
        if sum(arr[:i]) == sum(arr[i+1:]):
            return i
    return -1