Directi Interview Questions, Process, and Tips

Round duration - 60 minutes
Round difficulty - Medium

There were 2 coding questions. All of them were pretty easy and solvable in less than 40 minutes. Some string and pattern matching + some number theory problems were there.

Q1. 
Maximum Product Subarray Problem Statement
Given an array of integers, determine the contiguous subarray that produces the maximum product of its elements.
Explanation:
A subarray can be derived from th...read more
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Q2. 
Postfix Expression Evaluation Problem Statement
Given a postfix expression, your task is to evaluate the expression. The operator will appear in the expression after the operands. The output for each expr...read more
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Round duration - 60 minutes
Round difficulty - Hard

This was a technical round. First after properly introducing ourselves(me and the interviewer), we started with the main interview. I was asked 2 questions, one DS and Algorithms and the other System Design question.

Q1. 
Problem Statement: Sibling Nodes
You are provided with a Binary Tree consisting of 'N' nodes, where each node holds an integer value. Your objective is to identify and list all nodes that do not possess a...read more
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Q2. 
Merge Overlapping Intervals Problem Statement
Given a specified number of intervals, where each interval is represented by two integers denoting its boundaries, the task is to merge all overlapping interv...read more
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Q3. Design a streaming service similar to Netflix and explain how it onboard new content.
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Round duration - 45 minutes
Round difficulty - Medium

This was a technical round.

Q1. 
Duplicate Elements in Array
You are provided with an array or list called ARR, consisting of N integers. These integers fall within the range from 0 to N - 1. Some elements in this array may appear more t...read more
Ans. 
Concept of indexing can be used to solve this question.
Traverse the array. For every element at index i,visit a[i]. If a[i] is positive, then change it to negative. If a[i] is negative, it means the element has already been visited and thus it is repeated. Print that element.
Pseudocode :
findRepeating(arr[], n)
{
	missingElement = 0
	for (i = 0; i < n; i++){
		element = arr[abs(arr[i])]

		if(element < 0){
...read more
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Q2. 
Find Triplets with Given Sum Problem Statement
Given an array ARR consisting of N integers, your task is to identify all distinct triplets within the array that sum up to a given integer K.
Explanation:
...read more
Ans. 
Sorting can be used to solve this problem. Next, two -pointer technique can be applied on the sorted array.
Traverse the array and fix the first element of the triplet. Now use the Two Pointer technique to find if there is a pair whose sum is equal to x – array[i].
• Algorithm : 
1. Sort the given array.
2. Loop over the array and fix the first element of the possible triplet, arr[i].
3. Then fix two pointers, one at i...read more
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Round duration - 45 minutes
Round difficulty - Medium

This was a technical interview round with questions on Programming and algorithms.

Q1. 
Box Stacking Problem Statement
Consider you are provided with 'n' different types of rectangular 3D boxes. For each type of box, you have three separate arrays: height, width, and length that define the d...read more
Ans. 
• Make an integer matrix ‘boxes’ of dimension (3*n, 3), we will store all three rotations of each type of boxes in it.
• Generate all 3 rotations for all ‘n’ types of boxes, for simplicity we will consider ‘width’ always smaller than or equal to ‘length’. Store them in matrix ‘boxes’ such that ‘boxes[i][0]’, ‘boxes[i][1]’, ‘boxes[i][2]’ give height, width, length of ‘i’th box respectively.
• Sort the matrix ‘boxes’ in decreasi...read more
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Q2. 
Maximum Sum Subarray Problem Statement
Given an array of integers, find the maximum sum of any contiguous subarray within the array.
Example:
Input:
array = [34, -50, 42, 14, -5, 86]
Output:
137
Exp...read more
Ans. 
The direct approach to solve this problem is to run two for loops and for every subarray check if it is the maximum sum possible. 
Time complexity: O(N^2), Where N is the size of the array.
Space complexity: O(1)
The efficient approach is to use Kadane's algorithm. It calculates the maximum sum subarray ending at a particular index by using the maximum sum subarray ending at the previous position. 
Steps : 
D...read more
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Round duration - 50 minutes
Round difficulty - Medium

This was a difficult on to face as we have to hold phone and concentrate and explaining is also very difficult.

Q1. 
Stock Buy and Sell Problem Statement
Given an array/list 'prices' where the elements represent yesterday's stock prices at each minute, determine the maximum profit possible from a single buy and sell act...read more
Ans. 
The idea is to traverse the given list of prices and find a local minimum of every increasing sequence. We can gain maximum profit if we buy the shares at the starting of every increasing sequence (local minimum) and sell them at the end of the increasing sequence (local maximum). 
Steps :
1. Find the local minima and store it as starting index. If not exists, return.
2. Find the local maxima. and store it as an endi...read more
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Q2. 
Dijkstra's Algorithm Problem Statement
Given an undirected graph with 'V' vertices (labeled 0, 1, ..., V-1) and 'E' edges, where each edge connects two nodes ('X', 'Y') and has a weight that denotes the di...read more
Ans. 
Dijkstra's Algorithm basically starts at the source node and it analyzes the graph to find the shortest path between that node and all the other nodes in the graph.
The algorithm keeps track of the currently known shortest distance from each node to the source node and it updates these values if it finds a shorter path.
Once the shortest path between the source node and another node is found, that node is marked as "visi...read more
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Round duration - 30 minutes
Round difficulty - Easy

This was a small interaction just to make us familiar in Mumbai office.