Buyhatke Interview Questions and Answers

2 hours of basic dsa

Q1. What are foreign keys
Ans. 
Foreign keys are columns in a database table that reference the primary key of another table, establishing a relationship between the two tables.
• Foreign keys ensure referential integrity in a database by enforcing relationships between tables.

• They help maintain data consistency by preventing actions that would violate the relationships between tables.

• For example, in a database with tables for 'orders' and 'customers', ...read more
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Q2. Implement depth first search in tree
Ans. 
Depth first search in tree is implemented using recursion to explore each branch fully before moving to the next.
• Start at the root node and recursively visit each child node before moving to the next sibling node.

• Use a stack to keep track of nodes to visit, pushing children onto the stack before siblings.

• Base case is when the current node is null or a leaf node, then backtrack to the parent node.
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Round duration - 90 minutes
Round difficulty - Medium

Q1. 
Time to Burn Tree Problem
You are given a binary tree consisting of 'N' unique nodes and a start node where the burning will commence. The task is to calculate the time in minutes required to completely b...read more
Ans. 
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 completely

• Return the maximum time taken to burn the entire tree
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Q2. 
0/1 Knapsack Problem Statement
A thief is planning to rob a store and can carry a maximum weight of 'W' in his knapsack. The store contains 'N' items where the ith item has a weight of 'wi' and a value of...read more
Ans. 
Yes, the 0/1 Knapsack problem can be solved using dynamic programming with a space complexity of not more than O(W).
• Use a 1D array to store the maximum value that can be stolen for each weight capacity from 0 to W.

• Iterate through each item and update the array based on whether including the item would increase the total value.

• The final value in the array at index W will be the maximum value that can be stolen.
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Q3. 
Shortest Route Problem Statement
You want to visit your friend’s house located at some position in an infinite grid starting from origin (0, 0). You can move in four directions: East (E), West (W), North ...read more
Ans. 
Given a directional string representing a route to a friend's house in an infinite grid, find the shortest lexicographically smallest route to reach the destination.
• Iterate through the directional string and keep track of the movements in each direction (E, W, N, S).

• Calculate the final position based on the movements and find the shortest lexicographically smallest route to reach that position.

• Consider the constraints ...read more
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