LeetCode "Integer Break"

class Solution(object):
    def __init__(self):
        self.hm = {}

    def integerBreak(self, n):
        if n in self.hm:
            return self.hm[n]
        ret = 0            
        for i in range(1, n//2 + 1):
            v1 = self.integerBreak(i)
            v2 = self.integerBreak(n - i)
            ret = max(ret, v1 * v2, v1 * (n - i), i * v2, i * (n - i))
        self.hm[n] = ret            
        return ret