---
tags: leetcode
---

# [1352. Product of the Last K Numbers](https://leetcode.com/problems/product-of-the-last-k-numbers/)
# My Solution
## The Key Idea for Solving This Coding Question
## C++ Code

class ProductOfNumbers {
public:
    ProductOfNumbers() {
        startIdx = prefixProduct.size();
        prefixProduct.push_back(1);
    }

    void add(int num) {
        if (num == 0) {
            startIdx = prefixProduct.size();
            prefixProduct.push_back(1);
            return;
        }
        prefixProduct.push_back(prefixProduct.back() * num);
    }

    int getProduct(int k) {
        int idx = prefixProduct.size() - 1 - k;
        if (idx >= startIdx) {
            return prefixProduct.back() / prefixProduct[idx];
        }
        return 0;
    }

private:
    vector<int> prefixProduct;
    int startIdx;
};
/**
 * Your ProductOfNumbers object will be instantiated and called as such:
 * ProductOfNumbers* obj = new ProductOfNumbers();
 * obj->add(num);
 * int param_2 = obj->getProduct(k);
 */

### Time Complexity
* ProductOfNumbers: O(1)
* add: O(1)
* getProduct: O(1)
### Space Complexity
* ProductOfNumbers: O(1)
* add: O(1)
* getProduct: O(1)
# Miscellaneous
<!--
# Test Cases

["ProductOfNumbers","add","add","add","add","add","getProduct","getProduct","getProduct","add","getProduct"]
[[],[3],[0],[2],[5],[4],[2],[3],[4],[8],[2]]

* Time Limit Exceeded
https://leetcode.com/problems/product-of-the-last-k-numbers/submissions/839202062/
-->