Data Structures & Algorithms Test

This skill focuses on understanding how arrays and C-strings work at a memory and pointer level—critical for most DSA operations implemented in C. Candidates must handle indexing, iteration patterns, prefix sums, in-place updates, and boundary checks, while also understanding how C strings differ from byte buffers due to null-termination. Many DSA algorithms rely on contiguous memory and predictable indexing behavior, making array operations central to performance. This skill ensures candidates can safely manipulate buffers, avoid overruns, interpret pointer/array decay, and implement algorithms like sliding windows and prefix sums efficiently in C

This skill evaluates the candidate’s ability to correctly use pointers, pointer arithmetic, references, and indirect memory access—essential building blocks for implementing linked structures, dynamic arrays, and efficient algorithmic patterns. Understanding how arrays decay to pointers, how memory layouts influence indexing, and how to avoid undefined behavior is critical in C. Candidates must also demonstrate competence in swap patterns, pass-by-pointer semantics, and avoiding common pitfalls such as pointer aliasing, uninitialized memory, or out-of-bounds access. Strong pointer fluency is required for implementing any dynamic or recursive data structure safely and efficiently.

This skill assesses the ability to design and manipulate struct types used to represent composite data essential in DSA implementations—nodes, edges, records, contexts, and algorithmic metadata. Candidates must understand memory layout, alignment, copying semantics, pass-by-value vs pass-by-pointer behavior, and safe modification of struct fields. These concepts are critical because struct misuse can lead to silent bugs, unintended copies, incorrect mutation, and algorithmic inefficiencies. This skill ensures candidates can implement tree nodes, graph records, linked list nodes, or custom metadata correctly and predictably while maintaining memory safety.

This skill evaluates the candidate’s understanding of fundamental algorithmic operations implemented manually in C with full control over memory. This includes correct swap patterns, in-place modifications without extra buffers, linear scanning, recursive breakdown of problems, and safe loop boundaries. These constructs form the backbone of implementing sorting, searching, rotation, aggregation, and other low-level DSA behaviors. Mastery here demonstrates readiness to translate high-level DSA ideas into correct C code while handling undefined behavior risks and maintaining predictable performance on constrained systems.

This skill tests a candidate’s ability to mentally simulate C program execution—critical for debugging, correctness, and reasoning about complex DSA logic. Candidates must analyze loops, condition flows, pointer movements, and numerical transformations step by step. This includes tracing GCD logic, cumulative operations, in-place updates, array transformations, and multi-step pointer changes. The ability to dry-run code ensures clarity of thought, reduces runtime debugging, and demonstrates deep comprehension of how C actually executes instructions. This skill is essential for identifying off-by-one errors, undefined behavior triggers, recursion limits, and logical flaws in DSA implementations.

This skill evaluates a candidate’s ability to recognize and avoid C-language behaviors that commonly break data-structure and algorithm implementations. These include undefined behavior (UB), pointer aliasing, incorrect format specifiers, signed/unsigned mismatches, off-by-one errors, array bound violations, misuse of sizeof, uninitialized variables, wrong modulo normalization, and dangerous constructs like i = i++. Candidates must understand how subtle C semantics can silently corrupt memory, invalidate algorithmic logic, or crash production systems. Mastery of these pitfalls ensures the ability to write safe, predictable, and portable DSA code in C across compilers and architectures.