20+ DE Shaw Software Developer Intern Interview Questions and Answers

The problem involves finding the K maximum sum combinations from two arrays by adding one element from each array.

• Iterate through all possible sum combinations of elements from arrays A and B.

• Store the sums in a max heap to keep track of the K maximum sums.

• Pop the top K elements from the max heap to get the K maximum sum combinations.

Given an array of water buckets, find the minimum liters of water to remove to make all buckets equal.

• Iterate through the array to find the maximum frequency of a water amount

• Calculate the total liters to be removed by subtracting the maximum frequency from the total number of buckets

• Return the total liters to be removed as the answer

Find the minimum number of fountains to activate to water the entire garden.

• Iterate through the array to find the coverage of each fountain.

• Keep track of the farthest coverage reached by each activated fountain.

• Activate the fountain that covers the farthest distance not yet covered.

• Repeat until the entire garden is watered.

Verify if a given binary tree is a Binary Search Tree (BST) or not.

• Check if the left subtree of a node contains only nodes with values less than the node's value.

• Check if the right subtree of a node contains only nodes with values greater than the node's value.

• Ensure that both the left and right subtrees are also binary search trees.

• Return true if the tree is a BST, false otherwise.

• Handle cases with duplicate elements in either subtree.

Implement a function to delete a node from a linked list at a specified position.

• Traverse the linked list to find the node at the specified position.

• Update the pointers of the previous and next nodes to skip the node to be deleted.

• Handle cases where the position is at the beginning or end of the linked list.

• Ensure to free the memory of the deleted node to avoid memory leaks.

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.

The task is to find the total number of ways to make change for a specified value using given denominations.

• Use dynamic programming to solve this problem efficiently.

• Create a 2D array to store the number of ways to make change for each value up to the specified value.

• Iterate through each denomination and update the array accordingly.

• The final answer will be stored in the last cell of the array.

• Example: For N=3, D=[1, 2, 3], V=4, the output is 4 as explained in the example.

The problem involves arranging balls of different types in a straight line without having two adjacent balls of the same type.

• Use recursion to try all possible arrangements while keeping track of the previous ball type.

• Handle edge cases where one or more types of balls have a count of 0.

• Consider using dynamic programming to optimize the solution by storing intermediate results.

• For the given example input (2 1 1), the output is 6 as there are 6 valid arrangements.

• For the input...read more

The task is to determine the maximum profit achievable with at most K transactions by buying and selling stocks.

• Iterate through the array and keep track of the minimum price to buy and maximum profit for each transaction.

• Use dynamic programming to store the maximum profit at each day with each possible number of transactions.

• Consider edge cases like when K is 0 or when the array is empty.

• Example: For input N = 6, PRICES = [3, 2, 6, 5, 0, 3], K = 2, the output would be 7.

Find the position of the only '1' bit in the binary representation of a given non-negative integer.

• Iterate through the bits of the integer to find the position of the lone '1' bit.

• Use bitwise operations to check if there is exactly one '1' bit in the binary representation.

• Return the position of the lone '1' bit or -1 if there isn't exactly one '1'.

Find the length of the longest common subsequence among three strings.

• Use dynamic programming to solve this problem efficiently.

• Create a 3D array to store the lengths of common subsequences.

• Iterate through the strings to fill the array and find the longest common subsequence length.

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 and calculate the maximum profit that can be achieved by buying and selling at different points.

• Keep track of the maximum profit after the first transaction and the maximum profit overall by considering different combinations of buy and sell points.

• Consider edge cases where the stock prices ...read more

Validate if a binary tree is a Binary Search Tree (BST) or not.

• Check if the left subtree of a node contains only nodes with data less than the node's data.

• Check if the right subtree of a node contains only nodes with data greater than the node's data.

• Ensure that both the left and right subtrees are also binary search trees.

• Traverse the tree in an inorder manner and check if the elements are in sorted order.

• Use recursion to validate each node and its subtrees.

Find the length of the longest strictly increasing subsequence of heights of students in a row.

• Iterate through the heights array and for each student, find the length of the longest increasing subsequence ending at that student.

• Use dynamic programming to keep track of the longest increasing subsequence length for each student.

• Return the maximum length found in the dynamic programming array as the result.

• Example: For heights [10, 20, 10, 30, 40], the longest increasing subsequ...read more

Find the first negative integer in every window of size K in an array.

• Iterate through the array using a sliding window approach of size K

• For each window, find the first negative integer and add it to the result array

• If no negative integer is found in a window, add 0 to the result array

Detect if an array contains a Pythagorean triplet by checking if x^2 + y^2 = z^2.

• Iterate through all possible triplets of numbers in the array and check if they form a Pythagorean triplet.

• Use a nested loop to generate all possible combinations of three numbers from the array.

• Check if the sum of squares of two numbers is equal to the square of the third number.

The task is to distribute candies to students based on their performance while minimizing the total candies distributed.

• Create an array to store the minimum candies required for each student.

• Iterate through the students' ratings array to determine the minimum candies needed based on the adjacent ratings.

• Consider both left-to-right and right-to-left passes to ensure fair distribution.

• Calculate the total candies required by summing up the values in the array.

• Example: For rating...read more

Validate if a given binary tree is a Binary Search Tree (BST) or not.

• Check if the left subtree of a node contains only nodes with data less than the node's data

• Check if the right subtree of a node contains only nodes with data greater than the node's data

• Recursively check if both left and right subtrees are also binary search trees

Find the duplicate number in an array of integers from 0 to (N-2).

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

• Return the number with a count greater than 1 as the duplicate number.

• Alternatively, use Floyd's Tortoise and Hare algorithm to find the duplicate number in O(N) time and O(1) space.

The problem involves counting the number of distinct ways to climb N stairs by taking 1 or 2 steps at a time.

• Use dynamic programming to solve the problem efficiently.

• The number of ways to reach the Nth stair is the sum of the number of ways to reach the (N-1)th stair and the (N-2)th stair.

• Handle base cases where N=0 and N=1 separately.

• Consider using modulo operation to avoid overflow when dealing with large numbers.

Calculate the time in minutes required to completely burn a binary tree starting from a given node.

• Start burning from the given node and spread fire to adjacent nodes each minute

• Track the time taken for each node to burn and return the maximum time taken

• Use a queue to keep track of nodes to be burned next

Calculate the minimum number of candies needed to distribute to students based on their performance grades.

• Create an array to store the minimum candies needed for each student.

• Iterate through the students' ratings from left to right, comparing each student with the previous one to determine the candy count.

• Iterate through the students' ratings from right to left, comparing each student with the next one to ensure the correct candy count.

• Sum up the total candies needed for all...read more

Count the number of '1's in the binary form of a given integer.

• Convert the given integer to binary representation

• Count the number of '1's in the binary representation

• Return the count of '1's as output

Find the minimum amount of water to be removed to equalize water in buckets.

• Iterate through the array to find the average water level.

• Calculate the total amount of water that needs to be removed to equalize the buckets.

• Keep track of the excess water in each bucket and sum them up to get the final result.