300+ Faysal M. Qahtani Sons Interview Questions and Answers

Next Greater Element Using Stacks - find the next greater element for each element in an array using stack data structure.

• Create an empty stack and push the first element of the array onto it.

• Iterate through the array from the second element.

• While the stack is not empty and the current element is greater than the top element of the stack, pop the stack and set the popped element's next greater element as the current element.

• Push the current element onto the stack.

• For the rema...read more

Optimizing a recursive function

• Identify and eliminate unnecessary recursive calls

• Use memoization to store and reuse previously computed results

• Consider converting the recursive function to an iterative one if possible

Hashmap has O(1) time complexity for insertion, deletion, and retrieval in average case.

• Hashmap uses hashing to store key-value pairs, allowing for constant time access.

• Insertion, deletion, and retrieval operations have O(1) time complexity on average.

• In worst case scenarios, time complexity can degrade to O(n) due to collisions.

• Example: HashMap map = new HashMap<>();

Count the number of inversions in an array.

• An inversion occurs when a larger number appears before a smaller number in an array.

• Use a divide and conquer approach to solve the problem.

• Merge sort can be used to count the number of inversions in an array.

Find the median of two sorted arrays

• Merge the two arrays into one sorted array and find the median

• Use binary search to find the median efficiently

• Handle edge cases like arrays of different lengths

The minimum cost of ropes can be calculated using a greedy algorithm approach.

• Calculate the cost of joining two smallest ropes at each step

• Add the cost to the total cost and update the list of ropes

• Repeat until only one rope is left

Trapping rain water problem involves calculating the amount of water that can be trapped between buildings given their heights.

• Calculate the maximum height on the left and right of each building

• Subtract the building height from the minimum of the two maximum heights to get the water trapped at that building

• Sum up the water trapped at each building to get the total trapped water

Reverse a singly linked list and return the reversed list.

• Iterate through the linked list and reverse the pointers

• Use three pointers to keep track of current, previous, and next nodes

• Update the head pointer to the last node after reversing

Find the minimum number of jumps needed to reach the end of an array.

• Iterate through the array and keep track of the maximum reachable index at each step.

• Update the maximum reachable index as you iterate through the array.

• Increment the jump count when you reach the current maximum reachable index.

Design a checkout cart system for online shopping

• Store user's selected items in a cart

• Allow users to add, remove, and update quantities of items in the cart

• Calculate total price including taxes and shipping fees

• Provide secure payment options

• Generate order confirmation with unique order ID

The Rotten Oranges problem involves determining the minimum time required to rot all oranges in a grid.

• Create a queue to store the coordinates of rotten oranges

• Iterate through the grid and add all rotten oranges to the queue

• Use BFS to rot adjacent fresh oranges and update their status

• Continue the process until no fresh oranges are left or all oranges are rotten

The depth of a binary tree is the number of edges on the longest path from the root node to a leaf node.

• Depth of a binary tree can be calculated recursively by finding the maximum depth of its left and right subtrees and adding 1.

• For example, a binary tree with only a root node has a depth of 0, while a binary tree with one root node and two leaf nodes has a depth of 1.

• The depth of a binary tree can also be visualized as the level of the deepest leaf node in the tree.

To find the middle of a linked list, use the two-pointer approach.

• Initialize two pointers, slow and fast, pointing to the head of the linked list.

• Move the slow pointer one step at a time and the fast pointer two steps at a time.

• When the fast pointer reaches the end of the list, the slow pointer will be at the middle.

Merge k sorted linked lists into one sorted linked list

• Use a min heap to keep track of the smallest element from each list

• Pop the smallest element from the heap and add it to the merged list

• Add the next element from the list of the popped element to the heap

Design a chess game with all the necessary components and rules.

• Create a board with 64 squares (8x8 grid)

• Assign pieces to each player (16 pieces per player)

• Implement movement rules for each piece (e.g. pawn moves forward, bishop moves diagonally)

• Include special moves like castling and en passant

• Implement win conditions (checkmate, stalemate)

• Consider implementing features like undo move, AI opponent

Depth-first search (DFS) is a graph traversal algorithm that explores as far as possible along each branch before backtracking.

• DFS starts at a selected node and explores as far as possible along each branch before backtracking.

• It uses a stack to keep track of nodes to visit next.

• DFS can be implemented recursively or iteratively.

• Example: DFS traversal of a graph starting from node A: A -> B -> D -> E -> C -> F

Find two numbers in an array that add up to a specific target value.

• Use a hashmap to store the difference between the target value and each element in the array.

• Iterate through the array and check if the current element's complement exists in the hashmap.

• Return the indices of the two numbers that add up to the target value.

To find the sum of numbers, iterate through the array and add each number to a running total.

• Iterate through the array of numbers

• Add each number to a running total

• Return the total sum

Invert a binary tree by swapping left and right children of each node.

• Start from the root node and swap its left and right children.

• Recursively invert the left and right subtrees.

• Continue this process until all nodes are inverted.

Share market design involves creating a platform for buying and selling stocks and other financial instruments.

• Design a user-friendly interface for traders to view stock prices and place orders

• Implement a secure payment system for transactions

• Include real-time data updates for accurate pricing information

• Create a database to store user information and transaction history