AP CSA Unit 4.5: Find Maximum Algorithm Practice
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Unit 4, Section 4.5
Day 5 Practice • January 11, 2026
🎯 Focus: Array Algorithms - Find Maximum
Practice Question
Consider the following code segment:
int[] arr = {3, 7, 2, 9, 4};
int max = arr[0];
for (int i = 1; i < arr.length; i++) {
if (arr[i] > max) {
max = arr[i];
}
}
System.out.println(max);What is printed as a result of executing this code segment?
What This Tests: Section 4.5 covers array algorithms. The find-maximum pattern starts with the first element as the assumed max, then compares each subsequent element, updating max when a larger value is found.
Step-by-Step Trace
| i | arr[i] | arr[i] > max? | max |
|---|---|---|---|
| - | - | Initial | 3 |
| 1 | 7 | 7 > 3? Yes | 7 |
| 2 | 2 | 2 > 7? No | 7 |
| 3 | 9 | 9 > 7? Yes | 9 |
| 4 | 4 | 4 > 9? No | 9 |
The Find-Max Pattern
// Standard find-maximum pattern:
int max = arr[0]; // 1. Start with first element
for (int i = 1; i < arr.length; i++) { // 2. Start loop at index 1
if (arr[i] > max) { // 3. Compare each element
max = arr[i]; // 4. Update if larger
}
}Common Mistakes
Mistake: Answer A (3)
This is the FIRST element, not the maximum. The algorithm finds that 9 is larger than all other elements.
Mistake: Answer C (4)
This is the LAST element, not the maximum. The algorithm doesn't just return the last value—it tracks the largest seen.
Related Algorithms
Similar Patterns
Find minimum: Change > to <
Find index of max: Track maxIndex instead of max
Count occurrences: Use == and increment counter
Difficulty: Medium • Time: 3 minutes • AP Skill: 2.D - Array algorithms
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