Citadel Interview Questions and Answers

Round duration - 60 minutes
Round difficulty - Easy

The interviewer called my via phone and simultaneously provided me a link where I had to write the code for a given problem. It was scheduled at 12:30 pm, so timing was not an issue. It was a standard DP question involving a 2D matrix. The question was easy and I was able to code it within given time.

Round duration - 60 minutes
Round difficulty - Easy

The interviewer asked me two coding questions in this round.

Q1. Write an efficient program to find the sum of the contiguous subarray within a one-dimensional array of numbers that has the largest sum.
Ans. 
Efficient program to find sum of largest contiguous subarray within a one-dimensional array.
• Use Kadane's algorithm to find the maximum sum subarray in O(n) time complexity.

• Initialize max_sum and current_sum to 0, iterate through array updating current_sum and max_sum.

• Return max_sum as the result.
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Round duration - 60 minutes
Round difficulty - Easy

This was on-site round at their Bangalore office. The interviewer was friendly and helpful. The interview held inside a conference room.

Q1. 
DFS Traversal Problem Statement
Given an undirected and disconnected graph G(V, E), where V is the number of vertices and E is the number of edges, the connections between vertices are provided in the 'GR...read more
Ans. 
DFS traversal problem to find connected components in an undirected and disconnected graph.
• Use Depth First Search (DFS) algorithm to traverse the graph and find connected components

• Maintain a visited array to keep track of visited vertices

• Iterate through all vertices and perform DFS on unvisited vertices to find connected components
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Round duration - 60 minutes
Round difficulty - Easy

This was the next round of the onsite interviews. Took place in the same conference room as that of the previous round.

Round duration - 60 minutes
Round difficulty - Easy

This was the third round of the onsite interview. 
 

Round duration - 90 minutes
Round difficulty - Medium

3 coding Questions:
1st : Easy question based on simple loop iteration
2nd :Medium level Dp question 
3rd : Medium level tree question(where we were not just required to complete the tree function but to build whole bst from 
scratch) 

It was conducted from 1:30 - 3:00 pm.
The coding platform was very good (as auto indentation and auto completion of brackets were there)
having camera on.

Q1. 
Selling Stock Problem Statement
You are given the stock prices for N days. Each day i signifies the price of a stock on that day. Your goal is to calculate the maximum profit that can be achieved by buyin...read more
Ans. 
Calculate maximum profit by buying and selling stocks on different days.
• Iterate through the stock prices and buy on the day when the price is lower than the next day's price, and sell on the day when the price is higher than the next day's price.

• Keep track of the total profit earned by summing up the differences between buying and selling prices.

• Return the total profit as the maximum profit that can be earned.
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Q2. 
Minimum Time to Burn a Binary Tree from a Leaf Node
You are given a binary tree with 'N' unique nodes, and a specific start node from where the fire will begin. The task is to determine the time in minute...read more
Ans. 
The task is to determine the time in minutes required to burn the entire binary tree starting from a given node.
• Traverse the tree from the given start node to calculate the time taken to burn the entire tree.

• Use a queue to keep track of nodes and their burning time.

• Increment the burning time for each level of nodes until the entire tree is burned.
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Round duration - 75-80 minutes
Round difficulty - Hard

This was a completely technical coding round where I was asked to solve the problems of data structures.
The codepad where i was asked to code was fine,
The interviewer was very friendly and was helpful and understanding.
I also asked him about his work and experience in the company and some other questions.

Q1. 
Matrix Maximum Path Sum Problem
Given an N*M matrix filled with integer numbers, your task is to find the maximum path sum starting from any cell in the first row and ending at any cell in the last row. Y...read more
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Round duration - 45 minutes
Round difficulty - Easy

It was held on Gmeet platform
The interviewer was very experienced person and was very nice too.
He made me comfortable by first introducing himself in a very detailed way and then asking me mine introduction
Since I feel that his internet connection was not very good so he turned off his camera but I decided not to turn off mine as in online interviews your face reviles your confidence 
the interviewer mostly asked me questions about my interests in technical field and the project that I have done

Round duration - 150 mintues
Round difficulty - Medium

Nice goes i good environment.

Q1. 
Buy and Sell Stock Problem Statement
Imagine you are Harshad Mehta's friend, and you have been given the stock prices of a particular company for the next 'N' days. You can perform up to two buy-and-sell ...read more
Ans. 
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 a...read more
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Round duration - 90 minutes
Round difficulty - Easy

It happens in a nice environment but internet connection was week.

Q1. 
Delete a Node from a Linked List
You are provided with a linked list of integers. Your task is to implement a function that deletes a node located at a specified position 'POS'.
Input:
The first line co...read more
Ans. 
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 edge cases such as deleting the head or tail of the linked list.

• Ensure to free the memory of the deleted node to avoid memory leaks.
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It was easy and main question wweer from mathr

Question from dsa cp segment tress