Data Structures and Algorithms Flashcards

An echocardiography AI model must select the single best view from a real-time stream of 30 frames per second. Which algorithmic strategy minimizes latency while maintaining acceptable accuracy?

Answer: Sliding window with early-exit on high-confidence prediction

A sliding window with early-exit terminates as soon as a high-confidence frame is detected, reducing average latency without sacrificing reliability on clear views.

What is the space complexity of storing a full adjacency matrix for a graph representing the connectivity of 1,000 cardiac mesh nodes?

Answer: O(n²)

An adjacency matrix for n nodes requires an n×n grid of entries, so space grows as O(n²)—for 1,000 nodes that is 1,000,000 entries.

A technician applies a median filter to a 2D echocardiographic image to reduce speckle noise. What does the median filter algorithm do at each pixel?

Answer: Replaces the pixel with the middle value in its sorted neighborhood

A median filter sorts the intensity values of a pixel's neighborhood and replaces the pixel with the median (middle) value, effectively suppressing outlier speckle noise.

When indexing a large echocardiography database by patient ID using a hash function, what collision resolution strategy chains multiple entries together at each hash bucket?

Answer: Separate chaining with linked lists

Separate chaining stores colliding keys in a linked list (or other structure) at each bucket, allowing multiple patients to share the same hash value.

In dynamic programming applied to cardiac motion segmentation, the 'optimal substructure' property means:

Answer: The optimal global segmentation can be built from optimal subsegmentations of smaller image regions

Optimal substructure means the globally optimal solution is composed of optimal solutions to overlapping sub-problems, which is the key property that makes dynamic programming applicable.

A priority queue is used to schedule echocardiographic post-processing tasks by clinical urgency. Which underlying data structure gives O(log n) insert and O(log n) extract-minimum?

Answer: Min-heap

A min-heap maintains the heap property in O(log n) for both insertion and extraction of the minimum element, making it the standard backing structure for priority queues.

In run-length encoding (RLE) applied to compressing a sector-shaped echocardiographic image, performance is best when the image contains:

Answer: Long consecutive runs of identical or near-identical pixel values

RLE encodes consecutive identical values as a (value, count) pair; it achieves the highest compression ratio when the image has long homogeneous regions.