10+ Workfreaks Corporate Service Interview Questions and Answers

Sort an array of 0s and 1s in linear time without using additional arrays.

• Iterate through the array and maintain two pointers, one for 0s and one for 1s.

• Swap elements at the two pointers based on the current element being 0 or 1.

• Continue this process until the entire array is sorted in place.

Find the number with the maximum frequency in an array of integers.

• Iterate through the array and keep track of the frequency of each number using a hashmap.

• Find the number with the maximum frequency and return it.

• If multiple elements have the same maximum frequency, return the one that appears first.

Find the maximum sum of any contiguous subarray within an array of integers.

• Iterate through the array and keep track of the maximum sum of subarrays encountered so far.

• At each index, decide whether to include the current element in the subarray or start a new subarray.

• Update the maximum sum if a new maximum is found.

• Example: For array [34, -50, 42, 14, -5, 86], the maximum sum is 137.

• Example: For array [-5, -1, -8, -9], the maximum sum is -1.

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.

Find the shortest path in a binary matrix from a source cell to a destination cell consisting only of 1s.

• Use Breadth First Search (BFS) to explore all possible paths from the source cell to the destination cell.

• Keep track of visited cells to avoid revisiting them.

• Update the path length as you traverse through the matrix.

• Return the shortest path length found or -1 if no valid path exists.

Given an array representing an elevation map, find the maximum amount of rainwater that can be trapped between the bars.

• Iterate through the array and calculate the maximum height on the left and right of each bar.

• Calculate the trapped water by finding the minimum of the maximum heights on the left and right minus the current bar height.

• Sum up the trapped water for all bars to get the total trapped rainwater.

• Example: For input [0, 1, 0, 2], the trapped rainwater is 1 unit.

• Exam...read more

The task is to determine the maximum profit that can be achieved by performing up to two buy-and-sell transactions on a given set of stock prices.

• Iterate through the array of stock prices to find the maximum profit that can be achieved by buying and selling stocks.

• Keep track of the maximum profit that can be obtained by performing two transactions.

• Consider all possible combinations of buying and selling stocks to maximize profit.

• Ensure to sell the stock before buying again to...read more

Determine if Ninja can reach his friend's house with even x-coordinate without using modulus operator.

• Check if the x-coordinate is even or odd by using bitwise AND operation with 1.

• Return 1 if x-coordinate is even, else return 0.

• Handle multiple test cases by iterating through each input.

Implement a function to check if a given integer is a perfect square.

• Create a function that takes an integer as input and returns true if it is a perfect square, false otherwise.

• Iterate through possible square roots of the input integer and check if the square of the root equals the input.

• Return true if a perfect square is found, false otherwise.

The task is to print the bottom view of a binary tree from left to right.

• Traverse the binary tree in level order and keep track of the horizontal distance of each node from the root.

• Store the nodes at each horizontal distance in a map, updating it as you traverse the tree.

• After traversal, extract the bottom-most nodes at each horizontal distance to get the bottom view sequence.

Find the length of the longest substring with at most K distinct characters in a given string.

• Use a sliding window approach to keep track of the characters and their counts within the window.

• Maintain a hashmap to store the characters and their frequencies.

• Update the window size and characters count as you iterate through the string.

• Return the maximum window size encountered for each test case.

Find the K-th smallest element in an array of distinct integers.

• Sort the array and return the element at index K-1.

• Use a min-heap to find the K-th smallest element efficiently.

• Implement quickselect algorithm for optimal performance.

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

• Merge Sort is a divide-and-conquer algorithm that splits the array into two halves, recursively sorts each half, and then merges the sorted halves back together.

• Time complexity of Merge Sort is O(n log n) in the worst case scenario.

• It is a stable sorting algorithm, meaning that the relative order of equal elements is preserved.

• Example: Input: [5, 3, 8, 6, 2], Output: [2, 3, 5, 6, 8]

Find duplicates in an array of integers within a specified range.

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

• Return elements with count greater than 1 as duplicates.

• Time complexity can be optimized to O(N) using a set to store seen elements.

Implementing cart functionality in an e-commerce application involves managing user interactions, updating quantities, handling discounts, and processing orders.

• Create a data structure to store cart items, quantities, and prices.

• Implement add to cart, remove from cart, and update quantity functionalities.

• Handle discounts, promotions, and coupon codes.

• Calculate total price, including taxes and shipping costs.

• Implement checkout process to place orders and update inventory.

• Consi...read more

Implement multiple RecyclerViews on a magnified screen in an Android app by adjusting item sizes and spacing.

• Adjust item sizes and spacing based on screen magnification level

• Use nested RecyclerViews or custom layouts to display multiple lists

• Implement custom item decorators to manage spacing between RecyclerViews

• Consider using a GridLayoutManager with custom span sizes for each RecyclerView