7000+ Software Engineer Interview Questions and Answers

Merge K sorted arrays into a single sorted array.

• Iterate through all arrays and merge them into a single array.

• Use a min heap to efficiently merge the arrays.

• Implement a custom comparator function for the min heap.

• Time complexity can be optimized to O(N log K) using min heap.

Find the index of the first occurrence of string A in string B.

• Iterate through string B and check if a substring of length equal to A matches A.

• Return the index of the first occurrence of A in B, or -1 if not found.

Implement Merge Sort algorithm to sort a sequence of numbers in non-descending order.

• Use Divide and Conquer approach to recursively divide the input array into two halves.

• Merge the sorted halves to produce a completely sorted array.

• Ensure the time complexity is O(n log n) for sorting.

• Handle edge cases like empty array, single element array, etc.

Reverse a given string containing characters from [a-z], [A-Z], [0-9], and special characters.

• Iterate through the characters of the string from end to start and append them to a new string to get the reversed string.

• Use built-in functions like reverse() or StringBuilder in languages like Java for efficient reversal.

• Handle special characters and numbers along with alphabets while reversing the string.

• Ensure to print each reversed string on a separate line as per the output for...read more

To debug the slow behavior of the API, analyze network latency, check for database issues, monitor server performance, and review code for potential bottlenecks.

• Analyze network latency to identify any issues with data transmission.

• Check for database issues such as slow queries or insufficient indexing.

• Monitor server performance to ensure it has enough resources and is not overloaded.

• Review the code for potential bottlenecks, such as inefficient algorithms or excessive databas...read more

Find the sum of the subarray with the maximum sum among all subarrays in an array of integers.

• Iterate through the array and keep track of the maximum sum subarray seen so far.

• Use Kadane's algorithm to efficiently find the maximum subarray sum.

• Consider the case where all elements in the array are negative.

• Handle the case where the array contains only one element.

Merge two sorted arrays into one sorted array in place.

• Iterate from the end of both arrays and compare elements to merge in place

• Use two pointers to keep track of the current position in each array

• Handle cases where one array is fully merged before the other

Reverse words in a string word by word, removing leading/trailing spaces and extra spaces between words.

• Split the input string by spaces to get individual words

• Reverse the order of the words

• Join the reversed words with a single space in between

Implement a Sudoku solver to fill empty slots in a 9x9 grid with numbers 1-9 satisfying constraints.

• Create a recursive function to solve the Sudoku puzzle by trying out different numbers in empty slots.

• Use backtracking to backtrack and try a different number if a conflict is encountered.

• Ensure each number appears only once per row, column, and 3x3 grid.

• Return the completed Sudoku grid as the output.

The Water Jug Problem involves determining if a specific amount of water can be measured using two jugs of different capacities.

• Start by considering the constraints and limitations of the problem.

• Think about how the operations allowed can be used to reach the target measurement.

• Consider different scenarios and test cases to come up with a solution.

• Implement a function that takes the capacities of the jugs and the target measurement as input and returns True or False based on ...read more

Generate all possible valid parentheses configurations with N pairs.

• Use backtracking to generate all possible combinations of parentheses.

• Keep track of the number of open and close parentheses used.

• Add '(' if there are remaining open parentheses, and add ')' if there are remaining close parentheses.

Bubble Sort is used to sort an array of non-negative integers in non-decreasing order.

• Iterate through the array and compare adjacent elements, swapping them if they are in the wrong order.

• Repeat this process until the array is sorted.

• Time complexity of Bubble Sort is O(n^2) in worst case.

• Space complexity of Bubble Sort is O(1) as it sorts the array in place.

Find the maximum difference between any two elements in an array and determine if it is even or odd.

• Iterate through the array to find the maximum and minimum elements.

• Calculate the difference between the maximum and minimum elements.

• Check if the difference is even or odd and return the result.

Calculate the Nth Fibonacci number efficiently using dynamic programming.

• Use dynamic programming to store previously calculated Fibonacci numbers to avoid redundant calculations.

• Start with base cases F(1) and F(2) as 1, then iterate to calculate subsequent Fibonacci numbers.

• Return the Nth Fibonacci number as the final result.

Identify all prime numbers less than or equal to a given positive integer N.

• Iterate from 2 to N and check if each number is prime

• Use the Sieve of Eratosthenes algorithm for efficient prime number identification

• Optimize by only checking up to the square root of N for divisors

Given a railway seat number, determine if it is valid and identify its berth type.

• Parse input integer 't' for number of test cases

• For each test case, check if seat number is valid (1 <= N <= 100)

• Identify berth type based on seat number and output the result

• Possible berth types are Lower, Middle, Upper, Side Lower, and Side Upper

The task is to determine the total number of ways to make change for a specified value using given denominations.

• Create a dynamic programming table to store the number of ways to make change for each value up to the target value.

• Iterate through each denomination and update the table accordingly based on the current denomination.

• The final value in the table will represent the total number of ways to make change for the target value.

• Consider edge cases such as when the target v...read more

The challenge involves forming dance pairs from available boys and girls based on potential pairings to maximize the number of pairs.

• Parse the input to get the number of test cases, boys, girls, and potential pairings.

• Iterate through the potential pairings and form pairs based on the given indexes.

• Output '1' if a set of maximum possible pairs is returned, else output '0'.

• There can be multiple valid configurations of pairs.

• Example: For input '2 2 2' and pairings '1 1' and '2 2...read more

The task is to find the length of the longest consecutive sequence in an unsorted array of integers.

• Sort the array to bring consecutive numbers together

• Iterate through the sorted array and keep track of the current consecutive sequence length

• Update the maximum length if a longer sequence is found

The task is to determine the minimum number of platforms needed at a railway station based on arrival and departure times of trains.

• Sort the arrival and departure times in ascending order.

• Use two pointers to track overlapping schedules.

• Increment platform count when a new train arrives before the previous one departs.

Validate if a given string is a palindrome after removing special characters, spaces, and converting to lowercase.

• Remove special characters and spaces from the input string

• Convert the string to lowercase

• Check if the modified string is equal to its reverse to determine if it's a palindrome

Reverse a given stack of integers using recursion without using extra space or loops.

• Use recursion to pop all elements from the original stack and store them in function call stack

• Once the stack is empty, push the elements back in reverse order using recursion

• Use the top(), pop(), and push() methods to manipulate the stack

Develop an algorithm to compress a string by replacing consecutive duplicate characters with the character followed by the count of its repetitions.

• Iterate through the input string while keeping track of consecutive character counts.

• Replace consecutive duplicate characters with the character followed by the count if count exceeds 1.

• Ensure the count does not exceed 9 for each character.

• Return the compressed string as output.

Program for Fibonacci series for n terms with user input.

• Take user input for n

• Initialize variables for first two terms of Fibonacci series

• Use a loop to generate the series up to n terms

• Print the series

Interview questions for Software Engineer position

• Array manipulation and linked list operations

• Tree data structure and balancing techniques

• Database concepts and differences between SQL and NoSQL

• Web development frameworks and protocols

• Concepts of Deadlock and Race Condition

• Use of pointers in function oriented programming and their absence in Java

I will troubleshoot the router by checking the power supply, resetting the router, and checking the network settings.

• Check if the router is properly plugged in and receiving power

• Reset the router by turning it off and on again

• Check the network settings and make sure they are correct

• Try connecting to the router with a different device

• If all else fails, contact the internet service provider for assistance

The task is to determine the frequency of each character from 'a' to 'z' in a given string.

• Create an array of size 26 to store the frequency of each character from 'a' to 'z'.

• Iterate through the input string and increment the corresponding index in the array for each character encountered.

• Output the array of frequencies for each test case.

Find the greatest common divisor (GCD) of two given numbers 'X' and 'Y'.

• Implement a function to calculate the GCD of two numbers using Euclidean algorithm

• Iteratively find the remainder of dividing the larger number by the smaller number until the remainder is 0

• The last non-zero remainder is the GCD of the two numbers

4 people with different crossing times need to cross a bridge with one torch. Only 2 can cross at a time. What's the minimum time?

• The person with the longest time should always be accompanied by someone else

• The two fastest people should cross together to save time

• The torch needs to be brought back to the starting side every time two people cross

• The total time taken will be the sum of all individual crossing times

Print the left view of a binary tree given in level order form.

• Traverse the tree level by level and print the first node of each level (leftmost node).

• Use a queue to keep track of nodes at each level.

• Time complexity should be O(n) where n is the number of nodes in the tree.

Algorithm to find if a number is present in a sorted n x n matrix with linear time complexity.

• Start with the top right element

• Compare the element with x

• If equal, return its position

• If e < x, move down (if out of bounds, return false)

• If e > x, move left (if out of bounds, return false)

• Repeat till element is found or returned false

Modify a boolean matrix such that if any element is 1, set its entire row and column to 1.

• Iterate through the matrix and mark rows and columns to be modified

• Use additional arrays to keep track of rows and columns to be modified

• Update the matrix in-place based on the marked rows and columns

The problem is to determine whether a given string can be considered a K-Palindrome by removing up to 'k' characters.

• Iterate through the string from both ends and check if characters match, if not increment removal count

• If removal count is less than or equal to k, return True, else return False

• Use dynamic programming to optimize the solution by storing subproblem results

Identify the missing integer in an array of binary strings and return its binary representation without leading zeros.

• Iterate through the binary strings to convert them to integers and find the missing number using the formula for sum of integers from 0 to N.

• Calculate the sum of all integers from 0 to N using the formula (N*(N+1))/2 and subtract the sum of the integers in the array to find the missing number.

• Convert the missing integer to binary representation and return it a...read more

Develop a function to remove all instances of a given character from a string.

• Iterate through the string and build a new string excluding the specified character.

• Use a StringBuilder or similar data structure for efficient string manipulation.

• Handle edge cases such as empty string or character not found in the input string.

Identify and return all characters in a string that appear more than once along with their frequency.

• Iterate through the string and count the frequency of each character using a hashmap.

• Return characters with frequency greater than 1 in an array of tuples.

I stay up to date with emerging technologies and programming languages through various methods.

• I regularly read tech blogs and news websites to stay informed about the latest trends and advancements.

• I participate in online forums and communities where developers discuss new technologies and share their experiences.

• I attend conferences, workshops, and webinars to learn from industry experts and network with other professionals.

• I take online courses and tutorials to enhance my ...read more

Find the node where two linked lists merge, return -1 if no merging occurs.

• Traverse both lists to find the lengths and the difference in lengths

• Adjust the starting point of the longer list to match the length of the shorter list

• Traverse both lists in parallel until the nodes match, return the data of the matching node

Given an arithmetic expression, place parentheses to maximize the value of the expression.

• Identify the operators in the expression ('+', '-', '*').

• Consider the precedence of operators to determine where to place parentheses.

• Calculate the value of the expression with different placements of parentheses to find the maximum value.

Detect if an array contains a Pythagorean triplet by checking if there are three integers x, y, and z such that x^2 + y^2 = z^2.

• Iterate through all possible combinations of three integers in the array and check if x^2 + y^2 = z^2.

• Use a nested loop to generate all possible combinations efficiently.

• Return 'yes' if a Pythagorean triplet is found, otherwise return 'no'.

Reverse a singly linked list of integers.

• 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 list.

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

Merge nodes between zeroes in a linked list to store the sum of included nodes.

• Traverse the linked list and keep track of sum between zeroes

• Merge nodes between zeroes by updating the sum in the merged node

• Handle edge cases like empty list or single node between zeroes

• Ensure the list starts and ends with a zero

To reverse N cards, time complexity is O(N).

• The time complexity to reverse N cards is O(N).

• The algorithm needs to flip each card once, so the time complexity is linear.

• The time it takes to reverse all cards is directly proportional to the number of cards.

• For example, if there are 10 cards, it will take 10 flips to reverse all of them.

Reverse the order of elements in an array and display the reversed array.

• Create a function that takes an array as input

• Use a loop to iterate through the array and swap elements at opposite ends

• Return the reversed array

The problem is to find non-empty subsets of a given set of integers whose sum is zero.

• The problem is a special case of the knapsack problem and is known to be NP-Complete.

• A brute-force approach would involve generating all subsets and checking their sums.

• The brute-force approach has an exponential time complexity.

• There is no known polynomial time solution for this problem.

Given a 2D array, find elements where sum of cube of digits equals element itself and return (i * i + j * j) value.

• Iterate through the 2D array and check if the sum of cube of digits equals the element itself.

• Calculate (i * i + j * j) for such elements and return the values.

• If no such element exists, return -1.

Implement a function to multiply two sparse matrices and return the resulting matrix.

• Create a function that takes two sparse matrices as input and returns the resulting matrix after multiplication.

• Iterate through the non-zero elements of the matrices to perform the multiplication efficiently.

• Ensure to handle the sparse nature of the matrices to optimize the multiplication process.

• Consider the constraints provided to ensure the function works within the specified limits.

• Test t...read more