Lesson 8.1 · College Board Unit 4
2D Array Basics
A 2D Java array is an array of rows. grid.length counts rows, and grid[r].length counts elements in a particular row.
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Unit 8: 2D Arrays, Algorithms, and Data
The final unit combines grid traversal, the standard search and sort algorithms with their efficiency comparison, and the data topics that close the course.
Lessons and exercises
Lesson 8.2 · College Board Unit 4
2D Array Traversal
A row-major traversal finishes one row before moving to the next. Bounds must match the dimension indexed by each loop variable.
Lesson 8.3 · College Board Unit 4
Linear and Binary Search
Linear search works without sorted order. Binary search requires sorted data and discards half of the remaining interval after each comparison.
Lesson 8.4 · College Board Unit 4
Sorting and Efficiency
Selection sort repeatedly chooses the smallest remaining element. Insertion sort grows a sorted prefix by shifting larger values. Their usual nested-loop forms have quadratic worst-case work.
Lesson 8.5 · College Board Unit 4
Text Files and Scanner
A Scanner reads sequential input. Establish what tokens or lines the input contains before choosing a reading method, and close the scanner after use.
Lesson 8.6 · College Board Unit 4
Data and Its Implications
A technically correct program can still cause harm through unnecessary collection, biased sampling, or disclosure. Evaluate who is represented, who can access the data, and how long it is retained.
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