Maximum Number of Upgradable Servers — Python

# Time:  O(n)
# Space: O(1)

import itertools


# math
class Solution(object):
    def maxUpgrades(self, count, upgrade, sell, money):
        """
        :type count: List[int]
        :type upgrade: List[int]
        :type sell: List[int]
        :type money: List[int]
        :rtype: List[int]
        """
        # let x be the number of sold servers
        # (c-x)*u <= m+(x*s)
        # -x <= (m-c*u)//(u+s) <= 0
        # c-x <= c+(m-c*u)//(u+s) <= c
        return [min(c+(m-c*u)//(u+s), c) for c, u, s, m in itertools.izip(count, upgrade, sell, money)]