Self-assessment quiz
Presentation & objectives
The following quizzes are here to help you check that you understood the articles you had to study. At the end of a quiz, you will be given explanations on your answers. If some of them are wrong, you will have the possibility to click on the question you failed to try again.
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Quizzes
Recursive algorithms
# What sentence best describes a base case in a recursive function?
1. [x] The part of the function where the recursion stops and a result is returned
> ✅ The base case is essential to ensure recursion terminates, providing a result instead of calling the function again.
1. [ ] The part of the function that calls itself
> ❌ This describes recursion itself, not the base case which is crucial to stop recursion.
1. [ ] The maximum depth the recursion can reach
> ❌ Recursion depth is a different concept, usually relating to system limitations, not the base case.
1. [ ] The initial call to the recursive function
> ❌ The initial call is simply the first invocation of the recursive function, not the base case.
# Given the following recursive function, what will be the output of `foo(3)`?
```python
def foo (n: int) -> int:
if n == 0:
return 1
else:
return n - 1 * foo(n)
```
1. [ ] 6
> ❌ This is not the correct output due to issues in the recursive logic.
1. [x] The input is not getting "smaller", this leads to infinite recursion
> ✅ The input does not decrease, causing the function to keep calling itself indefinitely, leading to infinite recursion.
1. [ ] The base case is incorrect, this leads to infinite recursion
> ❌ The base case is valid (`n == 0`), but the problem is with the recursive step, not reducing `n` properly.
1. [ ] The recursive call is not always connected to the base: this may lead to infinite recursion
> ❌ The recursive call is connected to the base, but the problem lies in the way `n` is handled.
# Given the following recursive function, what will be the output of `bar(4)`?
```python
def bar (n: int) -> int:
if n == 0:
return 1
else:
return n + bar(n - 2)
```
1. [x] 7
> ✅ The recursive calls would be: `4 + bar(2)` which returns `4 + (2 + bar(0)) = 4 + 2 + 1 = 7`.
1. [ ] The input is not getting "smaller", this leads to infinite recursion
> ❌ The input does decrease by 2 each time, preventing infinite recursion.
1. [ ] The base case is incorrect, this leads to infinite recursion
> ❌ The base case is correct (`n == 0`), allowing the recursion to stop.
1. [ ] The recursive call is not always connected to the base: this may lead to infinite recursion
> ❌ The recursive call is correctly reducing the input and is connected to the base case.
# Given the following recursive function, what will be the output of `bar(3)`?
```python
def bar (n: int) -> int:
if n == 0:
return 1
else:
return n + bar(n - 2)
```
1. [ ] 4
> ❌ This is not the correct output based on how the recursive function progresses.
1. [ ] The input is not getting "smaller", this leads to infinite recursion
> ❌ The input does decrease by 2, so it is shrinking.
1. [ ] The base case is incorrect, this leads to infinite recursion
> ❌ The base case is correct and would stop the recursion.
1. [x] The recursive call is not always connected to the base: this may lead to infinite recursion
> ✅ Starting with `bar(3)`, it calls `bar(1)`, and then `bar(-1)` and so on, but there's no base case to handle `n < 0`, leading to potential infinite recursion.