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What does the following code output?
```java
public static int multiply(int a, int b) {
if (b == 0) {
return 0;
} else {
return multiply(a, b - 1) + a;
}
}
System.out.println(multiply(5, 3));
```
15
Identify the error in the following code:
```java
public static void recursiveMethod() {
do something
recursiveMethod(); // recursive call
}
```
Missing base case, which will cause infinite recursion and a stack overflow error.
What does the following code output?
```java
public static void traverseArray(ArrayList<Integer> array, int startIndex) {
if (startIndex == array.size() - 1) { // base case
System.out.println(array.get(startIndex));
} else { // recursive case
System.out.println(array.subList(startIndex, array.size()).get(0));
traverseArray(array, startIndex + 1);
}
}
ArrayList<Integer> arr = new ArrayList<>(Arrays.asList(1, 2, 3));
traverseArray(arr, 0);
```
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What is the definition of Recursion?
A way to simplify problems by having a subproblem that calls itself repeatedly.
What is the definition of a Recursive Method?
A method that has two parts: a base case and the recursive call.
What is the definition of a Base Case?
The last recursive call. When the base case is reached, the recursion is stopped and a value is returned.
What is the definition of Recursive Call?
A call to the recursive method itself, telling it to start over, either with the same or different parameters.
What is the definition of a Call Stack?
A stack that keeps track of all the times that the recursive function is called, as well as their individual parameters.
What is the purpose of the base case in recursion?
To stop the recursion and return a value, preventing an infinite loop.
What is the role of the call stack in recursion?
To keep track of all the recursive calls and their parameters, allowing the program to return values correctly.
What is the trade-off between recursion and iteration?
Recursion is often simpler to read but can be slower and use more memory due to the call stack.
How can recursion simplify problem-solving?
By breaking down a large problem into smaller, self-similar subproblems that can be solved repeatedly.
What are the two main parts of a recursive method?
The base case and the recursive call.
What is the relationship between recursion and iteration?
All recursive code can be written iteratively using loops.