Delhivery Software Developer Interview Questions, Process, and Tips

Round duration - 90 minutes
Round difficulty - Medium

This was a Data Structures round. Both questions were answered in optimal time complexity with clean code. Every other question was answered to the best of my knowledge

Q1. 
Rotting Oranges Problem Statement
You are given an undirected and disconnected graph G(V, E) with V vertices numbered from 0 to V-1 and E edges. Your task is to perform a BFS traversal starting from the 0...read more
Ans. Using queue
Let us consider a function BFS that accepts a list of edges, EDGES, and the number of vertices VERTEX as a parameter and do: 
1. Create ADJACENCYMATRIX from EDGES.
2. Define a boolean array VISITED to store nodes that are already visited.
3. Iterate over VISITED[i] for each 0<= i < VISITED.LENGTH, and check:
   1. If VISITED[i] is FALSE, call BFSHELPER function for ADJACENCYMATRIX, i and VISITED.
Now, the function BF...read more
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Q2. 
Smallest Integer Not Representable as Subset Sum
Given a non-decreasing sorted array ARR of N positive numbers, determine the smallest positive integer that cannot be expressed as the sum of elements from...read more
Ans. Brute force Approach
The brute force approach for this problem is explained below:
1. We can generate all possible 2 ^ N subsets where ‘N’ is the number of elements in the array.
2. Compute the sum of each subset.
3. Insert those sums into a HashSet and then
4. Run a loop i: 1 -> Integer.MAX_VALUE to check if ‘i’ is present in the hashSet. The first element that is missing from the hashSet is our answer.
 
We will use a recursive...read more
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Q3. 
BFS Traversal in a Graph
Given an undirected and disconnected graph G(V, E) where V vertices are numbered from 0 to V-1, and E represents edges, your task is to output the BFS traversal starting from the ...read more
Ans. Using queue
Let us consider a function BFS that accepts a list of edges, EDGES, and the number of vertices VERTEX as a parameter and do: 
1. Create ADJACENCYMATRIX from EDGES.
2. Define a boolean array VISITED to store nodes that are already visited.
3. Iterate over VISITED[i] for each 0<= i < VISITED.LENGTH, and check:
   1. If VISITED[i] is FALSE, call BFSHELPER function for ADJACENCYMATRIX, i and VISITED.
Now, the function BF...read more
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Round duration - 100 minutes
Round difficulty - Easy

Mostly technical and System Design questions were asked.

Q1. Design an LRU (Least Recently Used) cache.
Ans. 
Should be familiar with OS concepts
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