Tape equilibrium

tape.py

class Tape:
    def __init__(self, _array):
        self.array = _array
        if len(self.array) < 2:
            raise Exception("array must have at least 2 items")

    # without considering complexity -> because of using sum() function in for loop
    def getAnswer1(self):
        leftSum = rithtSum = 0
        diff = 999999999  # a big int number for the first comparison

        for i in range(1, len(self.array)):
            leftSum = sum(self.array[0:i])  # complexity issue
            rithtSum = sum(self.array[i:])  # complexity issue
            tempDiff = abs(leftSum - rithtSum)
            if tempDiff < diff:
                diff = tempDiff
        return diff
    # returns answer with considering complexity
    
    def getAnswer2(self):

        leftSum = self.array[0]
        rithtSum = sum(self.array[1:])  # this is not inside for loop so it's ok :)
        diff = abs(leftSum - rithtSum)

        for i in range(1, len(self.array) - 1):
            leftSum += self.array[i]
            rithtSum -= self.array[i]
            tempDiff = abs(leftSum - rithtSum)
            if tempDiff < diff:
                diff = tempDiff

        return diff


array = [3, 1, 2, 4, 3]
tape = Tape(array)
# print tape.getAnswer1()
print tape.getAnswer2()  # prints 1

array2 = [-10, 12, -7, 4]
tape2 = Tape(array2)
# print tape2.getAnswer1()
print tape2.getAnswer2()  # prints 5