SDE1 at Amazon

How it went

What they would tell you

How to prepare

Round by round

1. 1

   Online Assessment60 min

   Two coding problems along with a Work Style Assessment,I solved one and a half of the questions, and about two weeks later, I received a Hiring Interest Form. DSA-related questions asked were: Merge Intervals

   • Given a collection of intervals, the task was to merge any overlapping intervals and return a new list of non-overlapping intervals.

   • The solution required sorting and iterating through the intervals efficiently. Maximum Subarray Sum

   • The problem asked to find the contiguous subarray (within a one-dimensional numeric array) that has the largest sum.

   • This was a classic dynamic programming problem that could be solved using Kadane’s algorithm.

   • Merge Intervals
   • Maximum Subarray Sum
2. 2

   DSA60 min

   After completing the Online Assessment (OA). The round consisted of two coding problems and some Leadership Principles questions. Question 1 I was given an encoded string where each letter corresponds to a number, and in some cases, the frequency of the character was mentioned in parentheses. For example, the string "1226#24#(2)" translates to "abzxx". The encoding works like this: 'a' is 1, 'b' is 2, and so on. Characters like 'j' are encoded as 10#, 'k' as 11#, etc. If a character appears more than once, its frequency is appended next to it. The task was to calculate the frequency of each character in the string. Output: [1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 1] Question 2 The second problem involved finding the kth largest number from a sublist that starts at index k and goes till the last element of the list. For instance, if you’re given the list [4, 2, 1, 3] and k = 2, the expected output would be [2, 2, 3].

3. 3

   DSA60 min

   Consisted of two coding problems, along with two Leadership Principles discussions. Question 1 I was given an n x n grid where some cells had traps (marked as -1) and the others were free (marked as 0). The task was to find how many distinct paths there are from the top-left (0,0) to the bottom-right (n-1, n-1). You can only move right or down, and you can’t step on the trap cells. The follow-up was a bit more interesting. Now, each cell either contains a trap (-1) or a reward (a non-negative integer). The goal was to find the maximum reward I could collect along a valid path, again moving only right or down, and avoiding traps. If there’s no valid path, the answer should be 0. Question 2 In this question, I was given a number n. The task was to reduce n to 0 by performing the minimum number of operations, where in each operation, you subtract one of the digits of n from itself. For example, with n = 27, the minimum number of operations needed was 5.

4. 4

   Bar Raiser60 min

   The final round began with a quick introduction. The interviewer introduced himself, and then I shared a brief overview of my background and current role. He asked a few questions related to my experience and the work I’m doing right now. Next, we moved on to the coding problem. The challenge was to construct a Maximum Sum Linked List from two sorted linked lists that have some common nodes. It’s a fairly common problem, and you can easily find it online. I was able to come up with a working solution and explained my approach clearly. However, I missed a few edge cases at first, which the interviewer pointed out. With his hints, I quickly made the necessary changes and handled all the cases correctly.

   • Maximum Sum Linked List from Two Sorted Linked Lists

What came up