SumOnLeftAndRight.py

def find_even_index(arr):
    #your code here
    sum = 0
    for item in arr:
        sum += item
    
    sumOnLeft = 0
    sumOnRight = sum
    i = 0
    for item in arr:
        sumOnRight -= item
        if sumOnRight == sumOnLeft:
            return i
        i+=1
        sumOnLeft +=item
    return -1

	
Test.assert_equals(find_even_index([1,2,3,4,3,2,1]),3)
Test.assert_equals(find_even_index([1,100,50,-51,1,1]),1,)
Test.assert_equals(find_even_index([1,2,3,4,5,6]),-1)
Test.assert_equals(find_even_index([20,10,30,10,10,15,35]),3)
Test.assert_equals(find_even_index([20,10,-80,10,10,15,35]),0)
Test.assert_equals(find_even_index([10,-80,10,10,15,35,20]),6)
Test.assert_equals(find_even_index(range(1,100)),-1)
Test.assert_equals(find_even_index([0,0,0,0,0]),0,"Should pick the first index if more cases are valid")
Test.assert_equals(find_even_index([-1,-2,-3,-4,-3,-2,-1]),3)
Test.assert_equals(find_even_index(range(-100,-1)),-1)