Multiple Choice Questions on Nested Loops: High School Computer Science Exam Prep

📚 Quick Study Guide

• 🔑 Definition: Nested loops are loops placed inside other loops. The inner loop executes completely for each iteration of the outer loop.
• ⏱️ Execution: The number of times the inner loop runs is the product of the outer and inner loop's iterations. For example, if the outer loop runs 5 times and the inner loop runs 10 times, the inner loop's code executes 50 times.
• 🧮 Time Complexity: Nested loops often contribute to higher time complexity, like $O(n^2)$ or $O(n^3)$, where $n$ is the size of the input.
• 💡 Common Use Cases:
  • Matrix/2D array processing
  • Generating combinations and permutations
  • Searching and sorting algorithms (e.g., bubble sort)
• 📝 Key Considerations:
  • Optimize inner loops to minimize computations.
  • Be mindful of the potential for exponential time complexity.
  • Ensure proper loop termination conditions to avoid infinite loops.

💻 Practice Quiz

1. What is the output of the following code snippet?

           for i in range(3):
               for j in range(2):
                   print(i, j)
           

   1. A. 0 0 0 1 1 0 1 1 2 0 2 1
   2. B. 0 0 1 1 2 2
   3. C. 0 1 1 2 2 0
   4. D. Error
2. How many times will the inner loop execute in this code?

           for x in range(5):
               for y in range(10):
                   print(x + y)
           

   1. A. 5
   2. B. 10
   3. C. 15
   4. D. 50
3. Which of the following is a common application of nested loops?
   1. A. Calculating the square root of a number
   2. B. Processing elements in a 2D array
   3. C. Finding the factorial of a number
   4. D. Printing "Hello, World!"
4. What will be the value of `count` after executing this code?

           count = 0
           for a in range(4):
               for b in range(a):
                   count += 1
           print(count)
           

   1. A. 4
   2. B. 6
   3. C. 10
   4. D. 12
5. Consider the following code. What does it print?

           for i in range(1, 4):
               for j in range(1, i + 1):
                   print("*", end="")
               print()
           

   1. A. * *
   2. B. 1 12 123
   3. C. * *
   4. D. Error
6. Which of these loops will iterate the most number of times?
   1. A. `for i in range(10): for j in range(5): pass`
   2. B. `for i in range(20): for j in range(2): pass`
   3. C. `for i in range(5): for j in range(10): pass`
   4. D. All of the above iterate the same number of times.
7. What is the primary reason for avoiding deeply nested loops (e.g., more than 3 levels deep) in code?
   1. A. They are not supported by most programming languages.
   2. B. They always lead to syntax errors.
   3. C. They can significantly decrease performance and increase code complexity.
   4. D. They are harder to indent correctly.