[Daily Coding Problem] #10

[Daily Coding Problem] #15

Apr 4, 2020

Chào các bạn. Câu hỏi hôm nay như sau: Problem You run an e-commerce website and want to record the last N order ids in a log. Implement a data structure to accomplish this, with the following API: record(order_id): adds the order_id to the log get_last(i): gets the ith last element from the log. i is guaranteed to be smaller than or equal to N. You should be as efficient with time and space as possible.

[Daily Coding Problem] #14

Apr 4, 2020

Chào các bạn. Câu hỏi hôm nay như sau: Problem This problem was asked by Facebook. Given a stream of elements too large to store in memory, pick a random element from the stream with uniform probability. Vietsub: Cho một file chứa rất lớn số lượng số tự nhiên. Yêu cầu bạn chỉ được đọc qua file 1 lần (sequential read) và phải chọn được một số ngẫu nhiên trong đó sao cho xác suất mỗi phần tử được chọn là bằng nhau, và bằng 1/N, với N là số lượng phần tử trong file.

[Daily Coding Problem] #13

Apr 4, 2020

Chào các bạn. Câu hỏi hôm nay như sau: Problem The area of a circle is defined as πr^2. Estimate π to 3 decimal places using a Monte Carlo method. Hint: The basic equation of a circle is x2 + y2 = r2. Method Phương pháp Monte Carlo là dựa vào xác suất thống kê để tính toán số Pi. Theo đó thì : Giả sử ta có 1 bảng mục tiêu hình vuông 1x1.

[Daily Coding Problem] #12

Apr 4, 2020

Chào các bạn. Câu hỏi hôm nay như sau: Problem Given an integer k and a string s, find the length of the longest substring that contains at most k distinct characters. For example, given s = “abcba” and k = 2, the longest substring with k distinct characters is “bcb”.__ Method Ý tưởng của bài này là: Bắt đầu một chuỗi substring đầu tiên là ký tự đầu, sau đó thêm dần các ký tự tiếp của chuỗi sao cho số lượng ký tự unique không vượt quá k.

[Daily Coding Problem] #11

Apr 4, 2020

Chào các bạn. Câu hỏi hôm nay như sau: Problem There exists a staircase with N steps, and you can climb up either 1 or 2 steps at a time. Given N, write a function that returns the number of unique ways you can climb the staircase. The order of the steps matters. For example, if N is 4, then there are 5 unique ways: 1, 1, 1, 1 2, 1, 1 1, 2, 1 1, 1, 2 2, 2 What if, instead of being able to climb 1 or 2 steps at a time, you could climb any number from a set of positive integers X?

[Daily Coding Problem] #10

Apr 4, 2020

Chào các bạn. Câu hỏi hôm nay như sau: Problem Implement an autocomplete system. That is, given a query string s and a set of all possible query strings, return all strings in the set that have s as a prefix. For example, given the query string de and the set of strings [dog, deer, deal], return [deer, deal]. Hint: Try preprocessing the dictionary into a more efficient data structure to speed up queries.

[Daily Coding Problem] #9

Apr 4, 2020

Chào các bạn. Câu hỏi hôm nay như sau: Problem Implement a job scheduler which takes in a function f and an integer n, and calls f after n milliseconds. Code public class Main { public static void main(String[] args) { solution(() -> System.out.println("Hello World"), 10000); } public static void solution(Command command, int n) { new Timer().schedule(new TimerTask() { @Override public void run() { command.execute(); } }, n); } interface Command { void execute(); } } Source code https://github.

[Daily Coding Problem] #8

Apr 4, 2020

Chào các bạn. Câu hỏi hôm nay như sau: Problem Given a list of integers, write a function that returns the largest sum of non-adjacent numbers. Numbers can be 0 or negative. For example, [2, 4, 6, 2, 5] should return 13, since we pick 2, 6, and 5. [5, 1, 1, 5] should return 10, since we pick 5 and 5. Follow-up: Can you do this in O(N) time and constant space?

[Daily Coding Problem] #7

Apr 4, 2020

Chào các bạn. Câu hỏi hôm nay như sau: Problem A unival tree (which stands for “universal value”) is a tree where all nodes under it have the same value. Given the root to a binary tree, count the number of unival subtrees. For example, the following tree has 5 unival subtrees: 0 / \ 1 0 / \ 1 0 / \ 1 1 Code implementation private static int getUnivalCount(TreeNode node){ if (node == null)return 0; int count = getUnivalCount(node.

[Daily Coding Problem] #6

Apr 4, 2020

Chào các bạn. Câu hỏi hôm nay như sau: Problem This problem was asked by Facebook. Given the mapping a = 1, b = 2, … z = 26, and an encoded message, count the number of ways it can be decoded. For example, the message ‘111’ would give 3, since it could be decoded as ‘aaa’, ‘ka’, and ‘ak’. You can assume that the messages are decodable. For example, ‘001’ is not allowed.

[Daily Coding Problem] #10

Problem

Source code

Reference

Tu Bean