Introduction

In this blog post, we'll share the most commonly asked coding interview questions at Shopify. 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: Walking Robot Simulation

A robot on an infinite XY-plane starts at point (0, 0) facing north. The robot receives an array of integers commands, which represents a sequence of moves that it needs to execute. There are only three possible types of instructions the robot can receive: -2: Turn left 90 degrees. -1: Turn right 90 degrees. 1 <= k <= 9: Move forward k units, one unit at a time. Some of the grid squares are obstacles. The ith obstacle is at grid point obstacles[i] = (xi, yi). If the robot runs into an obstacle, it will stay in its current location (on the block adjacent to the obstacle) and move onto the next command. Return the maximum squared Euclidean distance that the robot reaches at any point in its path (i.e. if the distance is 5, return 25). Note: There can be an obstacle at (0, 0). If this happens, the robot will ignore the obstacle until it has moved off the origin. However, it will be unable to return to (0, 0) due to the obstacle. North means +Y direction. East means +X direction. South means -Y direction. West means -X direction. Example 1: Input: commands = [4,-1,3], obstacles = [] Output: 25 Explanation: The robot starts at (0, 0): Move north 4 units to (0, 4). Turn right. Move east 3 units to (3, 4). The furthest point the robot ever gets from the origin is (3, 4), which squared is 32 + 42 = 25 units away. Example 2: Input: commands = [4,-1,4,-2,4], obstacles = [[2,4]] Output: 65 Explanation: The robot starts at (0, 0): Move north 4 units to (0, 4). Turn right. Move east 1 unit and get blocked by the obstacle at (2, 4), robot is at (1, 4). Turn left. Move north 4 units to (1, 8). The furthest point the robot ever gets from the origin is (1, 8), which squared is 12 + 82 = 65 units away. Example 3: Input: commands = [6,-1,-1,6], obstacles = [[0,0]] Output: 36 Explanation: The robot starts at (0, 0): Move north 6 units to (0, 6). Turn right. Turn right. Move south 5 units and get blocked by the obstacle at (0,0), robot is at (0, 1). The furthest point the robot ever gets from the origin is (0, 6), which squared is 62 = 36 units away. Constraints: 1 <= commands.length <= 104 commands[i] is either -2, -1, or an integer in the range [1, 9]. 0 <= obstacles.length <= 104 -3 104 <= xi, yi <= 3 104 The answer is guaranteed to be less than 231.

Topics: Array, Hash Table, Simulation

Problem #2: Encode and Decode TinyURL

Note: This is a companion problem to the System Design problem: Design TinyURL. TinyURL is a URL shortening service where you enter a URL such as https://leetcode.com/problems/design-tinyurl and it returns a short URL such as http://tinyurl.com/4e9iAk. Design a class to encode a URL and decode a tiny URL. There is no restriction on how your encode/decode algorithm should work. You just need to ensure that a URL can be encoded to a tiny URL and the tiny URL can be decoded to the original URL. Implement the Solution class: Solution() Initializes the object of the system. String encode(String longUrl) Returns a tiny URL for the given longUrl. String decode(String shortUrl) Returns the original long URL for the given shortUrl. It is guaranteed that the given shortUrl was encoded by the same object. Example 1: Input: url = "https://leetcode.com/problems/design-tinyurl" Output: "https://leetcode.com/problems/design-tinyurl" Explanation: Solution obj = new Solution(); string tiny = obj.encode(url); // returns the encoded tiny url. string ans = obj.decode(tiny); // returns the original url after decoding it. Constraints: 1 <= url.length <= 104 url is guranteed to be a valid URL.

Topics: Hash Table, String, Design, Hash Function