Nielsen Senior Software Developer Interview Questions and Answers

Find the median of two sorted arrays efficiently using binary search.

• Combine both arrays and sort them, then find the median. Example: [1, 3] and [2] -> [1, 2, 3] -> median is 2.

• Use binary search to partition both arrays. This reduces time complexity to O(log(min(n, m))).

• Handle even and odd lengths separately. For even, average the two middle values; for odd, take the middle value.

The chmod command in Linux changes file permissions for users, groups, and others.

• chmod 755 filename: Sets read, write, execute for owner; read, execute for group and others.

• chmod u+x filename: Adds execute permission for the file owner.

• chmod g-w filename: Removes write permission from the group.

• chmod 644 filename: Sets read/write for owner; read for group and others.

Use SQL query with ORDER BY and LIMIT to find the nth highest salary of an employee.

• Use ORDER BY clause to sort salaries in descending order

• Use LIMIT to specify the nth highest salary

• Example: SELECT salary FROM employees ORDER BY salary DESC LIMIT n-1, 1

Types of joins in SQL include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN.

• INNER JOIN: Returns rows when there is at least one match in both tables.

• LEFT JOIN: Returns all rows from the left table and the matched rows from the right table.

• RIGHT JOIN: Returns all rows from the right table and the matched rows from the left table.

• FULL JOIN: Returns rows when there is a match in one of the tables.

BinarySearch algorithm using Recursion finds the target element in a sorted array by dividing the array in half at each step.

• Divide the array in half and compare the target element with the middle element

• If the target element is smaller, search the left half recursively

• If the target element is larger, search the right half recursively

• Repeat until the target element is found or the array is empty

Check if string s is a subsequence of string t.

• Iterate through both strings using two pointers.

• Compare characters of s and t, moving pointer in t only if characters match.

• If all characters of s are found in t in order, return true.

• Example: s = 'abc', t = 'ahbgdc' => true