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Backend Software Engineer Interview Questions

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9,104 backend software engineer interview questions shared by candidates

Where does a cache fit in this picture (of a server/application layout) Given unknown number of Transactions coming into your website, how do you derive statistics on the total for the 'last' 30 minute period using constant memory (the answering is bucketing) Draw a java 8 lambda that returns the sum of a collection of objects where total is greater than x ( a ridiculous question, I dont see how this relates to any particular job skill )
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Backend Developer

Interviewed at N26

3.5★
Mar 17, 2016

Where does a cache fit in this picture (of a server/application layout) Given unknown number of Transactions coming into your website, how do you derive statistics on the total for the 'last' 30 minute period using constant memory (the answering is bucketing) Draw a java 8 lambda that returns the sum of a collection of objects where total is greater than x ( a ridiculous question, I dont see how this relates to any particular job skill )

-find the right most element in tree if postorder and inorder is given -how many binary can made with 3 nodes - 5 -binary search questn -optional keyword in java 8 , null and absent value -which language in not JVM , groovy -time complexity to find min element in max heap. O(n) -which sort is not react same every time , quicksort -algorithm for the count-distinct problem, approximating the number of distinct elements in a multiset. - HyperLogLog
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Backend Developer

Interviewed at Tact.ai

4.5★
Jul 11, 2019

-find the right most element in tree if postorder and inorder is given -how many binary can made with 3 nodes - 5 -binary search questn -optional keyword in java 8 , null and absent value -which language in not JVM , groovy -time complexity to find min element in max heap. O(n) -which sort is not react same every time , quicksort -algorithm for the count-distinct problem, approximating the number of distinct elements in a multiset. - HyperLogLog

First round 1 car pool There is a car with capacity empty seats. The vehicle only drives east (i.e., it cannot turn around and drive west). You are given the integer capacity and an array trips where trips[i] = [numPassengersi, fromi, toi] indicates that the ith trip has numPassengersi passengers and the locations to pick them up and drop them off are fromi and toi respectively. The locations are given as the number of kilometers due east from the car's initial location. Return true if it is possible to pick up and drop off all passengers for all the given trips, or false otherwise. Example 1: Input: trips = [[2,1,5],[3,3,7]], capacity = 4 Output: false Example 2: Input: trips = [[2,1,5],[3,3,7]], capacity = 5 Output: true 2nd round 2. Product of Array Except Self Given an integer array nums, return an array answer such that answer[i] is equal to the product of all the elements of nums except nums[i]. The product of any prefix or suffix of nums is guaranteed to fit in a 32-bit integer. You must write an algorithm that runs in O(n) time and without using the division operation. Example 1: Input: nums = [1,2,3,4] Output: [24,12,8,6] Example 2: Input: nums = [-1,1,0,-3,3] Output: [0,0,9,0,0] 3. Longest Substring Without Repeating Characters 3. Longest Substring Without Repeating Characters Medium Topics Companies Hint Given a string s, find the length of the longest substring without repeating characters. Example 1: Input: s = "abcabcbb" Output: 3 Explanation: The answer is "abc", with the length of 3. Example 2: Input: s = "bbbbb" Output: 1 Explanation: The answer is "b", with the length of 1. Example 3: Input: s = "pwwkew" Output: 3 Explanation: The answer is "wke", with the length of 3. Notice that the answer must be a substring, "pwke" is a subsequence and not a substring. 3rd round Interview ask me to write function which will check win condition for X and O for n*n matrix as i have mention a tic tac toe game in my resume and after that he ask me to write a script in any language which can give me content of web page, in my case mcqs are their which i have to push in array along with it option and correct andwer.
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SDE-1 Backend Developer

Interviewed at Zupee

3.3★
Oct 16, 2024

First round 1 car pool There is a car with capacity empty seats. The vehicle only drives east (i.e., it cannot turn around and drive west). You are given the integer capacity and an array trips where trips[i] = [numPassengersi, fromi, toi] indicates that the ith trip has numPassengersi passengers and the locations to pick them up and drop them off are fromi and toi respectively. The locations are given as the number of kilometers due east from the car's initial location. Return true if it is possible to pick up and drop off all passengers for all the given trips, or false otherwise. Example 1: Input: trips = [[2,1,5],[3,3,7]], capacity = 4 Output: false Example 2: Input: trips = [[2,1,5],[3,3,7]], capacity = 5 Output: true 2nd round 2. Product of Array Except Self Given an integer array nums, return an array answer such that answer[i] is equal to the product of all the elements of nums except nums[i]. The product of any prefix or suffix of nums is guaranteed to fit in a 32-bit integer. You must write an algorithm that runs in O(n) time and without using the division operation. Example 1: Input: nums = [1,2,3,4] Output: [24,12,8,6] Example 2: Input: nums = [-1,1,0,-3,3] Output: [0,0,9,0,0] 3. Longest Substring Without Repeating Characters 3. Longest Substring Without Repeating Characters Medium Topics Companies Hint Given a string s, find the length of the longest substring without repeating characters. Example 1: Input: s = "abcabcbb" Output: 3 Explanation: The answer is "abc", with the length of 3. Example 2: Input: s = "bbbbb" Output: 1 Explanation: The answer is "b", with the length of 1. Example 3: Input: s = "pwwkew" Output: 3 Explanation: The answer is "wke", with the length of 3. Notice that the answer must be a substring, "pwke" is a subsequence and not a substring. 3rd round Interview ask me to write function which will check win condition for X and O for n*n matrix as i have mention a tic tac toe game in my resume and after that he ask me to write a script in any language which can give me content of web page, in my case mcqs are their which i have to push in array along with it option and correct andwer.

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