#Write a Python class to find the three elements that sum to zero from a set of n real numbers.
class py_solution:
     def threeSum(self, nums):
        nums, result, i = sorted(nums), [], 0
        while i < len(nums) - 2:
            j, k = i + 1, len(nums) - 1
            while j < k:
                if nums[i] + nums[j] + nums[k] < 0:
                    j += 1
                elif nums[i] + nums[j] + nums[k] > 0:
                    k -= 1
                else:
                    result.append([nums[i], nums[j], nums[k]])
                    j, k = j + 1, k - 1
                    while j < k and nums[j] == nums[j - 1]:
                        j += 1
                    while j < k and nums[k] == nums[k + 1]:
                        k -= 1
            i += 1
            while i < len(nums) - 2 and nums[i] == nums[i - 1]:
                i += 1
        return result

print(py_solution().threeSum([-25, -10, -7, -3, 2, 4, 8, 10]))


#Write a Python class to implement pow(x, n).
class py_solution:
       def pow(self, x, n):
        if x==0 or x==1 or n==1:
            return x 

        if x==-1:
            if n%2 ==0:
                return 1
            else:
                return -1
        if n==0:
            return 1
        if n<0:
            return 1/self.pow(x,-n)
        val = self.pow(x,n//2)
        if n%2 ==0:
            return val*val
        return val*val*x

print(py_solution().pow(2, -3));
print(py_solution().pow(3, 5));
print(py_solution().pow(100, 0));
