g1301_1400.s1352_product_of_the_last_k_numbers

Class ProductOfNumbers

java.lang.Object

g1301_1400.s1352_product_of_the_last_k_numbers.ProductOfNumbers

public class ProductOfNumbers
extends Object

1352 - Product of the Last K Numbers.

Medium

Design an algorithm that accepts a stream of integers and retrieves the product of the last k integers of the stream.

Implement the ProductOfNumbers class:

• ProductOfNumbers() Initializes the object with an empty stream.
• void add(int num) Appends the integer num to the stream.
• int getProduct(int k) Returns the product of the last k numbers in the current list. You can assume that always the current list has at least k numbers.

The test cases are generated so that, at any time, the product of any contiguous sequence of numbers will fit into a single 32-bit integer without overflowing.

Example:

Input [“ProductOfNumbers”,“add”,“add”,“add”,“add”,“add”,“getProduct”,“getProduct”,“getProduct”,“add”,“getProduct”] [[],[3],[0],[2],[5],[4],[2],[3],[4],[8],[2]]

Output: [null,null,null,null,null,null,20,40,0,null,32]

Explanation: ProductOfNumbers productOfNumbers = new ProductOfNumbers(); productOfNumbers.add(3); // [3] productOfNumbers.add(0); // [3,0] productOfNumbers.add(2); // [3,0,2] productOfNumbers.add(5); // [3,0,2,5] productOfNumbers.add(4); // [3,0,2,5,4] productOfNumbers.getProduct(2); // return 20. The product of the last 2 numbers is 5 * 4 = 20 productOfNumbers.getProduct(3); // return 40. The product of the last 3 numbers is 2 * 5 * 4 = 40 productOfNumbers.getProduct(4); // return 0. The product of the last 4 numbers is 0 * 2 * 5 * 4 = 0 productOfNumbers.add(8); // [3,0,2,5,4,8] productOfNumbers.getProduct(2); // return 32. The product of the last 2 numbers is 4 * 8 = 32

Constraints:

• 0 <= num <= 100
• 1 <= k <= 4 * 104
• At most 4 * 104 calls will be made to add and getProduct.
• The product of the stream at any point in time will fit in a 32-bit integer.

Constructor Summary

Constructors

Constructor and Description
ProductOfNumbers()

Method Summary

Modifier and Type	Method and Description
void	add(int num)
int	getProduct(int k)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ProductOfNumbers

public ProductOfNumbers()

Method Detail

add

public void add(int num)

getProduct

public int getProduct(int k)