leetcode1352

class ProductOfNumbers:
    def __init__(self):
        self.matrix = []
        self.preproducts = []
        self.length = 0
        self.zeros = set()

    def add(self, num: int) -> None:
        self.matrix.append(num)
        if num == 0:
            self.zeros.add(self.length)
        if self.length == 0:
            self.preproducts.append(num)
        else:
            pre = self.preproducts[-1]
            if pre == 0:
                self.preproducts.append(num)
            else:
                self.preproducts.append(num * pre)
        self.length += 1

    def getProduct(self, k: int) -> int:
        j = self.length - 1
        i = self.length - k - 1
        if j - i  == 1:
            return self.matrix[j]
        for x in self.zeros:
            if x > i and x <= j:
                return 0
        if i < 0:
            return self.preproducts[j]
        return self.preproducts[j] // self.preproducts[i] if self.preproducts[i] != 0 else self.preproducts[j]