10+ Unthinkable Solutions Interview Questions and Answers for Freshers

The task is to find the duplicate element in an array of integers.

• Iterate through the array and keep track of the frequency of each element using a hash map.

• Return the element with a frequency greater than 1.

• Alternatively, sort the array and check for adjacent elements with the same value.

The question asks to find the total amount of rainwater that can be trapped in the given elevation map.

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

• Calculate the amount of water that can be trapped on each bar by subtracting its height from the minimum of the maximum heights on both sides.

• Sum up the amount of water trapped on each bar to get the total amount of rainwater trapped.

The given string needs to be reversed word wise, keeping the individual words intact.

• Split the string into an array of words using a space as the delimiter.

• Reverse the array of words.

• Join the reversed array of words using a space as the separator to form the final reversed string.

The task is to sort an array of 0s, 1s, and 2s in increasing order.

• Use a three-pointer approach to partition the array into three sections: 0s, 1s, and 2s.

• Initialize three pointers: low, mid, and high. low points to the start of the array, mid points to the current element being processed, and high points to the end of the array.

• While mid <= high, perform the following checks: if arr[mid] == 0, swap arr[low] and arr[mid], increment low and mid. If arr[mid] == 1, increment mid...read more

The task is to find the second largest element in an array of integers.

• Iterate through the array and keep track of the largest and second largest elements.

• Initialize the largest and second largest variables with the first two elements of the array.

• Compare each element with the largest and second largest variables and update them accordingly.

• Return the second largest element at the end.

The question asks whether it is possible to sort an array by choosing a continuous subarray and reversing it.

• Check if the array is already sorted. If yes, return true.

• Find the first and last elements of the subarray that needs to be reversed.

• Check if the subarray is in non-decreasing order. If yes, return true.

• Check if the elements after the subarray are in non-increasing order. If yes, return true.

• Otherwise, return false.

Design a data structure to efficiently find the kth largest number in a stream of numbers.

• Implement a data structure that can store incoming numbers and efficiently retrieve the kth largest number.

• Support addition of numbers and retrieval of the kth largest number.

• Use a priority queue or heap data structure to maintain the k largest numbers in the stream.

• Handle queries of adding numbers and retrieving the kth largest number.

• Ensure the system can handle an indefinite length of...read more

Given a Binary Search Tree, determine if a node with a given integer exists.

• Traverse the BST in a way that compares the current node's data with the given integer 'X'.

• If the current node's data is equal to 'X', return True.

• If the current node's data is less than 'X', move to the right subtree; if greater, move to the left subtree.

• Repeat this process until a match is found or the end of the tree is reached.

Remove duplicates from an array while maintaining order.

• Use a set to keep track of unique elements.

• Iterate through the array and add elements to the set if not already present.

• Convert the set back to an array to maintain order.

SQL query to find second highest salary

• Use the ORDER BY clause to sort salaries in descending order

• Use the LIMIT clause to retrieve the second row

Star pattern is a common programming exercise to print a pattern of stars in a specific shape.

• Use nested loops to print the desired number of rows and columns.

• Use if-else statements to determine when to print a star or a space.

• Experiment with different loop conditions and print statements to create different patterns.

JavaScript is a scripting language used for web development, while Node.js is a runtime environment that allows JavaScript to run on the server side.

• JavaScript is a client-side scripting language used for creating interactive web pages.

• Node.js is a runtime environment that allows JavaScript to run on the server side.

• Node.js uses the V8 JavaScript engine from Google Chrome to execute code.

• Node.js provides a set of built-in modules that help in building server-side applications...read more

Joins are used in databases to combine rows from two or more tables based on a related column between them.

• Joins are used to retrieve data from multiple tables based on a related column.

• Common types of joins 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 t...read more

The largest area of a histogram is the maximum area that can be enclosed by a rectangle within the histogram bars.

• Calculate the largest area of a histogram by finding the maximum area of rectangles that can be formed within the histogram bars.

• This can be done by iterating through each bar and calculating the area of rectangles that can be formed with that bar as the height.

• Keep track of the maximum area found so far and return it as the largest area of the histogram.

Find the string with minimum length in an array of strings.

• Iterate through the array and keep track of the minimum length string

• Return the string with the minimum length

SQL query to join two tables and retrieve data from one table.

• Use JOIN keyword to combine tables based on a related column

• Specify the columns to retrieve using SELECT statement

• Add conditions using WHERE clause if needed