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Nested Iteration

Sophie Anderson

Sophie Anderson

6 min read

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Study Guide Overview

This guide covers nested loops in Java, including their core concept (a loop within a loop), execution order, and time complexity. It provides examples of nested loops used for finding prime numbers and printing triangle patterns. The guide also explains the use of break and continue within nested loops and their effects on loop execution. Finally, it offers exam tips focusing on tracing code, time complexity analysis, and common nested loop patterns.

🚀 AP Computer Science A: Nested Loops - Your Last-Minute Guide 🚀

Hey there! Let's get you prepped for those nested loop questions. This guide is designed to be quick, clear, and effective for your final review. Let's do this!

🔗 Nested Loops: The Core Concept

Key Concept

A nested loop is simply a loop inside another loop. Think of it like Russian nesting dolls – the inner loop completes all its iterations for each iteration of the outer loop.

loopOne {
  loopTwo {
    // Code to execute
  }
}
  • Outer Loop: Controls the overall iterations.
  • Inner Loop: Executes completely for each cycle of the outer loop.
Exam Tip

Pay close attention to how the loop variables change in both the inner and outer loops. This is key to understanding the output.

⏱️ Execution Order

  1. The outer loop starts.
  2. The inner loop starts and runs to completion.
  3. The outer loop moves to its next iteration.
  4. The inner loop restarts and runs to completion again.
  5. This process repeats until the outer loop finishes.
Quick Fact

If the outer loop runs 'n' times and the inner loop runs 'm' times for each outer loop iteration, the inner loop executes a total of n * m times.

🔗 Code Example: Finding Primes

java
public static ArrayList<Integer> findNPrimes(int n) {
    int prime = 2;
    ArrayList<Integer> primes = new ArrayList<Integer>();
    for (int i = 0; i < n; ...
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