1000+ Full Stack Developer Interview Questions and Answers

Given a binary matrix, perform queries to flip elements in rows/columns and count zeros in rows/columns.

• Iterate through each query and update the matrix accordingly

• For type 1 queries, flip the elements in the specified row/column

• For type 2 queries, count the number of zeros in the specified row/column

• Return the count of zeros for type 2 queries

Tower of Hanoi problem involves moving 'N' disks from one rod to another following specific rules in less than 2^N moves.

• Implement a recursive function to move disks from one rod to another while following the rules.

• Use the concept of recursion and backtracking to solve the Tower of Hanoi problem efficiently.

• Maintain a count of moves and track the movement of disks in a 2-D array/list.

• Ensure that larger disks are not placed on top of smaller disks during the movement.

• The solu...read more

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

Find the Lowest Common Ancestor of two nodes in a binary tree.

• Traverse the binary tree to find the paths from the root to nodes X and Y.

• Compare the paths to find the last common node, which is the Lowest Common Ancestor.

• Implement a recursive function to find the LCA efficiently.

• Handle edge cases such as when X or Y is the root node or when X or Y is not present in the tree.

Find the most frequent word in a paragraph that is not in a list of banned words.

• Split the paragraph into words and convert them to uppercase for case-insensitivity.

• Count the frequency of each word, excluding banned words.

• Return the word with the highest frequency in uppercase.

Convert Excel sheet column title to corresponding column number.

• Iterate through the characters in the string from right to left, starting with a result of 0.

• For each character, calculate its value by subtracting 'A' and adding 1, then multiply by 26 raised to the power of its position from the right.

• Add up all the calculated values to get the final column number.

• Example: For input 'AB', A=1, B=2, so result = (1 * 26^1) + (2 * 26^0) = 28.

Determine the number of unique strings in an array by applying swapping operations on odd and even indices.

• Iterate through each string in the array and check if it can be transformed into another string by swapping characters at odd and even indices.

• Keep track of unique strings by comparing them with all other strings in the array.

• Return the count of unique strings found in the array.

Calculate the rank of a matrix based on linearly independent column or row vectors.

• Determine the number of linearly independent column vectors or row vectors in the matrix.

• Use Gaussian elimination or row reduction to simplify the matrix and find the rank.

• The rank of a matrix is the maximum number of linearly independent vectors it contains.

The task is to find all duplicate elements in an array of integers.

• Iterate through the array and keep track of the count of each element using a hashmap.

• Return all elements from the hashmap with count greater than 1 as the duplicate elements.

Find all pairs of elements in an array that add up to a given target.

• Iterate through the array and store each element in a hashmap along with its index.

• For each element, check if the target minus the element exists in the hashmap.

• If found, print the pair of elements. If not found, print (-1, -1).

Minimum number of operations to make all elements in an array equal by performing addition, subtraction, multiplication, or division.

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

• Calculate the difference between the maximum and minimum elements.

• The minimum number of operations needed is the difference between the maximum and minimum elements.

Rearrange a list of numbers such that every second element is greater than its adjacent elements.

• Iterate through the array and swap elements if needed to satisfy the condition

• Keep track of the current and next elements to compare and swap

• Ensure that the swapped elements maintain the desired order

Program to compute factorial of a given integer 'n', with error handling for negative values.

• Create a function to calculate factorial using a loop or recursion

• Check if input is negative, return 'Error' if true

• Handle edge cases like 0 and 1 separately

• Return the calculated factorial value

The task is to reverse a 32-bit signed integer and handle overflow cases.

• Create a function that takes a 32-bit signed integer as input

• Reverse the integer while handling overflow cases

• Return the reversed integer or -1 if overflow occurs

Add two numbers represented as linked lists and return the sum as a linked list.

• Traverse both linked lists simultaneously while keeping track of carry from previous sum

• Create a new linked list to store the sum of the two numbers

• Handle cases where one linked list is longer than the other by padding with zeros

• Update the current node with the sum of corresponding nodes from both lists and carry

Find the maximum distance between two elements in an array where the element at the first index is less than or equal to the element at the second index.

• Iterate through the array and keep track of the minimum element encountered so far along with its index.

• Calculate the maximum distance by subtracting the current index from the index of the minimum element.

• Update the maximum distance if a greater distance is found while iterating.

• Return the maximum distance calculated.

Count substrings with exactly K distinct characters in a given lowercase string.

• Iterate through all substrings of length K and count distinct characters.

• Use a set to keep track of distinct characters in each substring.

• Increment count if number of distinct characters equals K.

The task is to find the number of distinct ways to climb from the 0th step to the Nth step, where each time you can climb either one step or two steps.

• Use dynamic programming to solve this problem

• Create an array to store the number of ways to reach each step

• Initialize the first two elements of the array as 1 and 2

• For each subsequent step, the number of ways to reach that step is the sum of the number of ways to reach the previous two steps

• Return the number of ways to reach th...read more

The task is to find and return the indices of local minima and local maxima in the given array.

• Iterate through the array and compare each element with its neighbors to determine if it is a local minima or maxima.

• Consider corner elements separately by comparing them with only one neighbor.

• Store the indices of local minima and maxima in separate lists.

• If there are no local minima or maxima, return -1 as the only row element in the 2-D list.

Determine the length of the shortest contiguous subarray that needs to be sorted to make the entire array sorted in ascending order.

• Iterate from left to right to find the first element out of order.

• Iterate from right to left to find the last element out of order.

• Calculate the length of the subarray between the two out of order elements.

Calculate the sum of all elements in an array of length N.

• Read the size of the array N and then read N integers as elements of the array.

• Iterate through the array and add each element to a running total to calculate the sum.

• Return the final sum as the output.

Find the minimum cost to make all elements of an array equal by changing them to the same value.

• Calculate the median of the array and find the sum of absolute differences between each element and the median.

• Sort the array and find the median element, then calculate the sum of absolute differences between each element and the median.

• If the array has an even number of elements, consider the average of the two middle elements as the median.

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.

• Use three pointers to keep track of the current, previous, and next nodes while reversing the linked list.

• Update the head of the reversed linked list as the last node encountered during the reversal process.

To ensure accurate project estimates, I follow a structured approach that includes analyzing requirements, breaking down tasks, and considering potential risks.

• Analyze project requirements thoroughly

• Break down tasks into smaller, manageable chunks

• Consider potential risks and challenges

• Use historical data to inform estimates

• Collaborate with team members to validate estimates

Count the total number of inversions in an integer array.

• Iterate through the array and for each pair of elements, check if the inversion condition is met.

• Use a nested loop to compare each pair of elements efficiently.

• Keep a count of the inversions found and return the total count at the end.

Ceil value of a key in a Binary Search Tree (BST) is the smallest integer greater than or equal to the given number.

• Traverse the BST to find the closest integer greater than or equal to the given key.

• Compare the key with the current node value and update the ceil value accordingly.

• Recursively traverse left or right subtree based on the key value to find the ceil value.

• Return the ceil value once found for each test case.

Given a matrix with coins and empty cells, collect maximum coins from boundary cells and adjacent cells.

• Iterate through the boundary cells and collect coins from them and their adjacent cells

• Keep track of visited cells to avoid collecting the same coin multiple times

• Use depth-first search or breadth-first search to explore adjacent cells