Data Structures and Algorithms Flashcards

Which tree traversal order visits nodes in ascending sorted order when applied to a binary search tree indexing echocardiographic study timestamps?

Answer: In-order (left, root, right)

In-order traversal of a binary search tree visits nodes from smallest to largest key, producing timestamps in chronological ascending order.

A cardiac segmentation pipeline uses memoization to avoid recomputing contour fitting for image patches already processed. This technique primarily trades:

Answer: Increased memory usage for reduced redundant computation

Memoization caches previously computed results in memory so they are not recalculated, exchanging additional memory consumption for faster execution.

Fast Fourier Transform (FFT) is used in echocardiography to convert tissue Doppler time-domain signals to frequency-domain spectra. Compared to the naive DFT, FFT reduces complexity from O(n²) to:

Answer: O(n log n)

The FFT algorithm exploits symmetry to reduce the discrete Fourier transform from O(n²) to O(n log n) operations.

An echo system parses nested XML DICOM Structured Reports where each node may have child nodes. Which data structure naturally models this hierarchical, nested relationship?

Answer: Tree

Trees model hierarchical parent-child relationships directly; each XML element is a node whose nested child elements are its subtree.

When two echocardiography databases are merged and duplicate patient records must be identified efficiently across millions of entries, which algorithmic technique scales best?

Answer: Hash-based deduplication grouping records by a key hash (O(n))

Hash-based deduplication groups records by a key hash in a single O(n) pass, making it the most scalable approach for large datasets.

A recursive depth-first traversal of a large 3D echocardiographic surface mesh risks exceeding the call stack limit. What is the standard mitigation?

Answer: Convert recursion to an explicit stack-based iterative algorithm

Replacing system recursion with an explicit stack simulates DFS iteratively, eliminating call stack overflow risk for deep or large graphs.

In the context of echocardiographic image processing, what does algorithmic 'time complexity' measure?

Answer: How the number of operations grows as a function of input size

Time complexity describes how the number of computational operations scales with input size (n), independent of hardware or constant factors.