#1352
Product of the Last K Numbers
specialist · 665 · lc medium +30 · 62.9% accepted · 2,153 likes · top 65%
Description
Design a class that accepts a stream of integers and quickly returns the product of the most recent k values. Implement ProductOfNumbers:
- ProductOfNumbers() Initializes an empty stream.
- void add(int num) Appends num to the stream.
- int getProduct(int k) Returns the product of the last k numbers (the stream is guaranteed to have at least k elements).
Products of any contiguous subsequence fit in a 32-bit signed integer.
Example 1:
Input
["ProductOfNumbers","add","add","add","add","add","getProduct","getProduct","getProduct","add","getProduct"]
[[],[3],[0],[2],[5],[4],[2],[3],[4],[8],[2]]
Example 2:
Output
[null,null,null,null,null,null,20,40,0,null,32]
Example 3:
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
Code
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