## Problem: Equilibrium point

• Difficulty: Easy

Given an array A your task is to tell at which position the equilibrium first occurs in the array. Equilibrium position in an array is a position such that the sum of elements below it is equal to the sum of elements after it.

Input:
The first line of input contains an integer T denoting the no of test cases then T test cases follow. First line of each test case contains an integer N denoting the size of the array. Then in the next line are N space separated values of the array A.

Output:
For each test case in a new  line print the position at which the elements are at equilibrium if no equilibrium point exists print -1.

Constraints:
1<=T<=100
1<=N<=100

Example:
Input:

2
1
1
5
1 3 5 2 2

Output:
1
3

Explanation:
1. Since its the only element hence its the only equilibrium point
2. For second test case equilibrium point is at position 3 as elements below it (1+3) = elements after it (2+2)

Implementation: Python 2.7

```def equilibrium_point(arr):
if len(arr) == 1:
return 1
s = sum(arr)
sum_so_far = arr[0]
for i in xrange(1, len(arr)):
#print s - (sum_so_far + arr[i])
if s - (sum_so_far + arr[i]) == sum_so_far:
return i+1
sum_so_far += arr[i]
else:
return -1

if __name__ == '__main__':
t = input()
for _ in xrange(t):
n, (l) = input(), (map(int, raw_input().split()))
print equilibrium_point(l)
```