Introduction

In this blog post, we'll share the most commonly asked coding interview questions at Booking.com. If you don't have months to study for your interviews, you can use AI tools like Chatmagic to generate solutions quickly and efficiently - helping you pass the interviews and get the job offer!

Problem #1: Integer to Roman

Seven different symbols represent Roman numerals with the following values: Symbol Value I 1 V 5 X 10 L 50 C 100 D 500 M 1000 Roman numerals are formed by appending the conversions of decimal place values from highest to lowest. Converting a decimal place value into a Roman numeral has the following rules: If the value does not start with 4 or 9, select the symbol of the maximal value that can be subtracted from the input, append that symbol to the result, subtract its value, and convert the remainder to a Roman numeral. If the value starts with 4 or 9 use the subtractive form representing one symbol subtracted from the following symbol, for example, 4 is 1 (I) less than 5 (V): IV and 9 is 1 (I) less than 10 (X): IX. Only the following subtractive forms are used: 4 (IV), 9 (IX), 40 (XL), 90 (XC), 400 (CD) and 900 (CM). Only powers of 10 (I, X, C, M) can be appended consecutively at most 3 times to represent multiples of 10. You cannot append 5 (V), 50 (L), or 500 (D) multiple times. If you need to append a symbol 4 times use the subtractive form. Given an integer, convert it to a Roman numeral. Example 1: Input: num = 3749 Output: "MMMDCCXLIX" Explanation: 3000 = MMM as 1000 (M) + 1000 (M) + 1000 (M) 700 = DCC as 500 (D) + 100 (C) + 100 (C) 40 = XL as 10 (X) less of 50 (L) 9 = IX as 1 (I) less of 10 (X) Note: 49 is not 1 (I) less of 50 (L) because the conversion is based on decimal places Example 2: Input: num = 58 Output: "LVIII" Explanation: 50 = L 8 = VIII Example 3: Input: num = 1994 Output: "MCMXCIV" Explanation: 1000 = M 900 = CM 90 = XC 4 = IV Constraints: 1 <= num <= 3999

Topics: Hash Table, Math, String

Problem #2: Reward Top K Students

You are given two string arrays positive_feedback and negative_feedback, containing the words denoting positive and negative feedback, respectively. Note that no word is both positive and negative. Initially every student has 0 points. Each positive word in a feedback report increases the points of a student by 3, whereas each negative word decreases the points by 1. You are given n feedback reports, represented by a 0-indexed string array report and a 0-indexed integer array student_id, where student_id[i] represents the ID of the student who has received the feedback report report[i]. The ID of each student is unique. Given an integer k, return the top k students after ranking them in non-increasing order by their points. In case more than one student has the same points, the one with the lower ID ranks higher. Example 1: Input: positive_feedback = ["smart","brilliant","studious"], negative_feedback = ["not"], report = ["this student is studious","the student is smart"], student_id = [1,2], k = 2 Output: [1,2] Explanation: Both the students have 1 positive feedback and 3 points but since student 1 has a lower ID he ranks higher. Example 2: Input: positive_feedback = ["smart","brilliant","studious"], negative_feedback = ["not"], report = ["this student is not studious","the student is smart"], student_id = [1,2], k = 2 Output: [2,1] Explanation: - The student with ID 1 has 1 positive feedback and 1 negative feedback, so he has 3-1=2 points. - The student with ID 2 has 1 positive feedback, so he has 3 points. Since student 2 has more points, [2,1] is returned. Constraints: 1 <= positive_feedback.length, negative_feedback.length <= 104 1 <= positive_feedback[i].length, negative_feedback[j].length <= 100 Both positive_feedback[i] and negative_feedback[j] consists of lowercase English letters. No word is present in both positive_feedback and negative_feedback. n == report.length == student_id.length 1 <= n <= 104 report[i] consists of lowercase English letters and spaces ' '. There is a single space between consecutive words of report[i]. 1 <= report[i].length <= 100 1 <= student_id[i] <= 109 All the values of student_id[i] are unique. 1 <= k <= n

Topics: Array, Hash Table, String, Sorting, Heap (Priority Queue)

Problem #3: Reconstruct Itinerary

You are given a list of airline tickets where tickets[i] = [fromi, toi] represent the departure and the arrival airports of one flight. Reconstruct the itinerary in order and return it. All of the tickets belong to a man who departs from "JFK", thus, the itinerary must begin with "JFK". If there are multiple valid itineraries, you should return the itinerary that has the smallest lexical order when read as a single string. For example, the itinerary ["JFK", "LGA"] has a smaller lexical order than ["JFK", "LGB"]. You may assume all tickets form at least one valid itinerary. You must use all the tickets once and only once. Example 1: Input: tickets = [["MUC","LHR"],["JFK","MUC"],["SFO","SJC"],["LHR","SFO"]] Output: ["JFK","MUC","LHR","SFO","SJC"] Example 2: Input: tickets = [["JFK","SFO"],["JFK","ATL"],["SFO","ATL"],["ATL","JFK"],["ATL","SFO"]] Output: ["JFK","ATL","JFK","SFO","ATL","SFO"] Explanation: Another possible reconstruction is ["JFK","SFO","ATL","JFK","ATL","SFO"] but it is larger in lexical order. Constraints: 1 <= tickets.length <= 300 tickets[i].length == 2 fromi.length == 3 toi.length == 3 fromi and toi consist of uppercase English letters. fromi != toi

Topics: Depth-First Search, Graph, Eulerian Circuit