Chap 8 (Recursion)

What is recursive thinking

The expectation of finding simpler versions of a large problem during the design process.

What is recursion in programming

When a method activates itself to solve a problem.

What is a recursive method

A method that calls itself to solve smaller versions of a problem.

What is the stopping case (base case)

A case where the problem is simple enough to be solved without recursion.

What is a recursive call

A method activating itself to solve a simpler instance of the same problem.

What happens if there is no stopping case

The recursion will not terminate and may cause a StackOverflowError.

How are digits extracted in writeVertical

Using number/10 for all but last digit and number % 10 for the last digit.

What does number/10 represent in recursion

A simpler version of the original number with one fewer digit.

What does number % 10 represent

The last digit of the number.

What is the purpose of writeVertical

To print the digits of a non-negative integer vertically.

How does recursion handle negative numbers in superWriteVertical

It prints a negative sign and calls itself with -number.

What is an activation record

A memory block storing parameters, local variables, and return location for a method.

What is the execution stack

A stack data structure that stores activation records during method calls.

What happens when a method is called

Execution pauses, information is saved, and a new activation record is created.

What happens when a method finishes

Its activation record is removed and execution returns to the previous method.

Why must recursive calls eventually stop

To prevent infinite recursion and program failure.

What is infinite recursion

When recursive calls never reach a stopping case.

What error occurs from infinite recursion

StackOverflowError.

What is a fractal

An object that exhibits similarity under magnification.

What is a random fractal

A fractal generated using random variations.

How is the midpoint calculated in randomFractal

midX = (leftX + rightX)/2 and midY = (leftY + rightY)/2.

What is delta in randomFractal

A random vertical shift applied to the midpoint.

What is the purpose of recursive calls in randomFractal

To generate fractals for smaller line segments.

What is the stopping condition in randomFractal

When the horizontal distance is small enough, draw a line.

What does drawLine do

Draws a line between two points on a Graphics object.

What is the role of the Graphics object

It allows drawing images using pixel coordinates.

What is the purpose of traverseMaze

To guide a user through a maze and back out.

What is the stopping case in traverseMaze

When the tapestry is found.

What is a dead end in the maze

A direction blocked by a wall or already visited.

Why does traverseMaze avoid revisiting spots

To prevent infinite loops.

What is backtracking

Returning to a previous point after exploring a path that failed.

What is exhaustive search

Trying all possible paths to find a goal.

What is the role of marking in maze traversal

To track visited locations and avoid repetition.

What does the inquire method do

Asks a yes/no question and returns true or false.

How does deadend determine a blocked path

By checking for a wall or a previously visited location.

What is the goal of the Teddy Bear game

To reach a target number of bears within a limited number of steps.

What are the two moves in the Teddy Bear game

Add increment bears or halve the bears if even.

What is the stopping case in bears method

When initial equals goal.

What happens when no steps remain in bears

The method returns false.

How does recursion help solve the bears problem

By exploring possible moves as smaller subproblems.

What is the purpose of the power method

To compute x raised to the power n.

How are negative exponents handled in power

By returning 1/power(x, -n).

What is the base case for exponentiation

When n equals 0, the result is 1.