Unit 2 Day 11: Nested Loops
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Unit 2: Selection and Iteration
Day 11 Practice - January 16, 2026
Focus: Nested Loops
Practice Question
Consider the following code segment:
int count = 0;
for (int i = 0; i < 3; i++)
{
for (int j = 0; j < 4; j++)
{
count++;
}
}
System.out.println(count);What is printed as a result of executing this code?
What This Tests: This question tests your understanding of how nested loops execute and how to count total iterations.
Key Concept: Nested Loop Iterations
In nested loops, the inner loop completes ALL its iterations for EACH iteration of the outer loop. Total iterations = outer × inner.
// Outer loop runs 3 times (i = 0, 1, 2)
// Inner loop runs 4 times for EACH outer iteration
// i=0: j runs 0,1,2,3 -> count becomes 4
// i=1: j runs 0,1,2,3 -> count becomes 8
// i=2: j runs 0,1,2,3 -> count becomes 12
// Total: 3 × 4 = 12Common Mistakes
Mistake: Answer A - Adding instead of multiplying
3 + 4 = 7 is wrong. The inner loop runs 4 times FOR EACH of the 3 outer iterations, so it's 3 × 4 = 12.
Mistake: Answer C or D - Only counting one loop
Don't ignore one of the loops. Both loops contribute to the total count.
Counting Nested Iterations
Quick Formula for Total Iterations
Total iterations = (outer loop count) × (inner loop count)
For independent loops (inner doesn't depend on outer variable):
- Outer: 0 to n-1 -> n iterations
- Inner: 0 to m-1 -> m iterations
- Total: n × m
Example: i < 3 gives 3 iterations, j < 4 gives 4 iterations -> 12 total
Difficulty: Medium - Time: 1-2 minutes - AP Skill: 1.A - Determine output
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