20+ Full Stack Engineer Interview Questions and Answers for Freshers

Generate all possible non-empty subsets of a given array of distinct integers.

• Use recursion to generate all subsets by including or excluding each element in the array.

• Maintain a current subset and iterate through the array to generate subsets.

• Print each subset as it is generated to get all possible non-empty subsets.

The task is to find the length of the longest palindromic subsequence in a given string.

• Iterate through the string and create a 2D array to store the lengths of palindromic subsequences.

• Use dynamic programming to fill the array based on the characters in the string.

• Consider the cases where characters match or do not match to update the array values.

• Return the length of the longest palindromic subsequence for each test case.

Check if two strings follow the same pattern based on bijection between letters and words.

• Iterate through each letter in T and corresponding word in S to create a mapping.

• Use a hashmap to store the mapping between letters and words.

• Check if the mapping is consistent for all test cases.

Reverse a singly linked list of integers and return the head of the reversed linked list.

• Iterate through the linked list and reverse the pointers to point to the previous node instead of the next node.

• Keep track of the current, previous, and next nodes while traversing the linked list.

• Update the head of the reversed linked list to be the last node encountered.

• Ensure to handle edge cases like an empty linked list or a single node in the list.

Implement a function to return the level order traversal of a binary tree of integers.

• Create a queue to store nodes for level order traversal

• Start with the root node and enqueue it

• While the queue is not empty, dequeue a node, print its value, and enqueue its children

• Repeat until all nodes are traversed

Count the number of subarrays in an array whose sum is divisible by a given integer K.

• Iterate through the array and keep track of the running sum modulo K.

• Use a hashmap to store the frequency of remainders.

• For each prefix sum, check how many previous prefix sums have the same remainder.

• Return the total count of subarrays with sum divisible by K.

Return an array where each element represents the count of smaller elements on its right side in the given array.

• Iterate through the array from right to left and maintain a sorted list of elements encountered so far.

• For each element, find its index in the sorted list to determine the count of smaller elements on its right side.

• Use binary search or segment trees for efficient searching and updating of the sorted list.

The task is to count the number of occurrences of the digit '1' in each number from 0 to N.

• Iterate through each number from 0 to N

• Convert each number to a string

• Count the number of occurrences of the digit '1' in the string representation of each number

• Return the total count of '1's

Given a linked list of ninja villages, find the next greater ninja strength in the nearest linked village.

• Traverse the linked list and store the elements in an array.

• Use a stack to keep track of elements with no next greater element found yet.

• Iterate through the array to find the next greater element for each village.

• Return the array of next greater elements for each village.

The minimum number of operations required to make all elements of the given array equal.

• The array is generated based on the formula ARR[i] = (2*i + 1).

• To equalize the array, increment one element and decrement another in each operation.

• The number of operations needed is equal to the difference between the maximum and minimum elements in the array.

The 0/1 Knapsack Problem involves maximizing the total value of items a thief can steal within a given weight limit.

• Dynamic programming can be used to solve this problem efficiently.

• Create a 2D array to store the maximum value that can be stolen at each weight capacity.

• Iterate through the items and update the array based on whether the item is included or not.

• The final answer will be the value at the last cell of the array.

Implement a function to count the number of distinct substrings in a given string using a trie data structure.

• Create a trie data structure to store the substrings of the input string.

• Traverse the trie to count the number of distinct substrings.

• Handle empty string as a distinct substring.

• Return the count of distinct substrings for each test case.

The task is to find the minimum number of operations required to convert one string into another using delete, replace, and insert operations.

• Use dynamic programming to solve the problem efficiently.

• Create a 2D array to store the edit distances between substrings of the two input strings.

• Fill up the array based on the minimum of three possible operations: insert, delete, or replace.

• Return the value at the bottom right corner of the array as the final edit distance.

Merge overlapping intervals and return sorted list by start time.

• Sort the intervals based on start time.

• Iterate through intervals and merge overlapping ones.

• Return the merged intervals sorted by start time.

Find the length of the longest contiguous subarray that sums to zero in an array of integers.

• Iterate through the array and keep track of the running sum and its corresponding index in a hashmap.

• If the running sum is seen again, calculate the length of the subarray by subtracting the current index from the index stored in the hashmap.

• Update the maximum length of the subarray as you iterate through the array.

Examples of OOP concepts using code and principles

• Encapsulation: Using private variables and getter/setter methods

• Inheritance: Creating subclasses that inherit properties and methods from a superclass

• Polymorphism: Implementing methods with the same name but different functionality in subclasses

API stands for Application Programming Interface. It defines the methods and data formats that applications can use to communicate with each other.

• API is a set of rules and protocols that allows different software applications to communicate with each other.

• REST API is a type of API that follows the principles of REST (Representational State Transfer) architecture.

• Cloud computing refers to the delivery of computing services over the internet, including storage, databases, net...read more