Placement Papers - MCQ Practice Questions

QuickSort uses O(log n) space for the recursion call stack in the average case.

BFS uses a Queue (FIFO) to explore nodes level by level. DFS uses a Stack (LIFO).

A power of 2 has only one bit set. n & (n-1) removes the rightmost set bit, so if result is 0, n is a power of 2.

MergeSort has O(n log n) worst-case and is stable. QuickSort is O(n²) worst-case, HeapSort is not stable.

XOR (exclusive OR) returns 1 only when bits are different. 1 XOR 1 = 0 because both bits are the same.

Memoization is an optimization technique where results of expensive function calls are cached and returned when same inputs occur again.

In a sorted array, median is at index n/2, which is accessed in constant time O(1).

Recursive DFS uses call stack space proportional to the height of the tree/graph. For balanced tree, it's O(log n); worst case O(n).

Exponentiation is right-associative in Python. 32 = 9, then 29 = 512

API Gateway is a server that acts as an intermediary between clients and microservices, handling routing, authentication, and load balancing.

Google designs distributed systems that can scale horizontally across many machines to handle billions of requests.

Eventual consistency means that if no new updates are made, all nodes will eventually see the same data, though there may be temporary inconsistencies.

CAP theorem states that distributed systems can guarantee at most two of: Consistency, Availability, and Partition tolerance.

MapReduce is a programming model for processing large datasets in parallel by mapping data and then reducing results.

A load balancer distributes network traffic across multiple servers to improve reliability and responsiveness.

The Internet Layer (Layer 3) handles IP addresses and routing. Transport Layer (Layer 4) handles ports.

Average speed = Total Distance / Total Time. Distance one way = 240 km. Time from A to B = $\frac{240}{60}$ = 4 hours. Time from B to A = $\frac{240}{40}$ = 6 hours. Total Distance = 480 km, Total Time = 10 hours. Average Speed = $\frac{480}{10}$ = 48 km/h.

Let the 4th number be x. Then 5th number = previous number + x. If 5th = 20 and 6th = 32, then 6th = 5th + 5th_previous, so 32 = 20 + (5th_previous). Therefore, 5th_previous = 12. Since 5th_previous is the 4th number, the answer is 12.

Understanding:

This question asks about the behavior of multiple post-increment operators on the same variable within a single function call in C.

Step 1: Identify the issue

In C, modifying the same variable more than once between two sequence points is undefined behavior. A function call does not impose any ordering on the evaluation of its arguments — the order in which `x++`, `x++`, and `x++` are evaluated is not specified by the C standard.

Step 2: Recognize the standard rule

The C standard (both C89 and C99) states that if a variable is modified more than once, or is modified and read for a purpose other than determining the new value, between two sequence points, the behavior is undefined. Here, `x` is modified three times with no intervening sequence points.

Step 3: Conclusion

Because this is undefined behavior, the compiler is free to produce any output — it could print "5 6 7", "7 6 5", or something entirely different depending on the compiler and platform. No specific output can be guaranteed.

Answer:

The code exhibits undefined behavior because `x` is modified multiple times between sequence points.

Quick Tip:

In C/C++ interviews, always flag any expression that increments or decrements the same variable multiple times in a single statement — this is a classic undefined behavior trap.

Understanding:

This question asks about the core function of Azure Virtual Network (VNet) in Microsoft Azure.

Step 1: Define Azure VNet

Azure Virtual Network (VNet) is the fundamental building block for private networks in Azure. It enables many types of Azure resources — such as Azure Virtual Machines — to securely communicate with each other, with the internet, and with on-premises networks.

Step 2: Eliminate incorrect options

DNS resolution is a separate service (Azure DNS). Container image storage is handled by Azure Container Registry. Auto-scaling of VMs is managed by Azure Virtual Machine Scale Sets. None of these are the primary purpose of a VNet.

Step 3: Confirm the correct answer

VNet is specifically a networking construct that provides isolation, segmentation, routing, and secure connectivity — its primary purpose is enabling secure communication among Azure resources, the internet, and on-premises infrastructure.

Answer:

The primary purpose of an Azure VNet is to enable secure communication between Azure resources, the internet, and on-premises networks.