Echopills Interview Questions and Answers

Create a new array with elements of given array in reverse order.

• Iterate through the given array in reverse order and copy elements to a new array.

• Ensure to handle edge cases like empty array or single element array.

• Use a temporary variable to swap elements for in-place reversal if required.

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.

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

• Ensure to handle edge cases like empty list or single node list.

• Time complexity should be O(N) and space complexity should be O(1).

Calculate maximum profit by buying and selling stocks multiple times.

• Iterate through the array of stock prices and find all increasing sequences of prices.

• Calculate profit for each increasing sequence and add them up to get the maximum profit.

• Make sure to sell before buying again to maximize profit.

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

• Traverse the binary tree to find the paths from the root to each node, then compare the paths to find the LCA.

• Use recursion to traverse the tree efficiently and find the LCA.

• Handle cases where one node is an ancestor of the other node.

• Consider edge cases like when one or both nodes are not present in the tree.

• Optimize the solution to achieve the desired time complexity.

I have worked with SQL queries and JOIN operations in database management projects.

• Used INNER JOIN to combine rows from two or more tables based on a related column between them.

• Utilized LEFT JOIN to return all rows from the left table and the matched rows from the right table.

• Implemented WHERE clause to filter rows based on specified conditions.

• Employed GROUP BY to group rows that have the same values into summary rows.

• Executed subqueries to nest one query within another que...read more