PS$4-$ Recursion

Deadline: December

In this assignment, you will learn how to apply recursion to solve different problems. Note that this assignment, like any other assignment, will be graded with additional different test cases. We will check your codes to make sure that your solutions use recursion.

You MUST USE RECURSION in each question.

You MUST NOT USE GLOBAL VARIABLES in any question.

You MUST NOT USE NESTED FUNCTIONS in any question.

You MUST NOT USE eval$()$ function in any question.

You MUST NOT USE ITERATION AT ALL $($No$,$ for or while loops, no iterating over a list or string, No list or dictionary comprehensions, $..$etc$)$

You CAN and should use string builtin functions $($Hint: However there is no need to use $.$split$())$Q$2$: Hierarchical Directory Parsing and File Summation

This question requires recursively parsing and analyzing a hierarchical directory structure represented as a nested string. The question has three parts.

You MUST USE RECURSION in each question.

You MUST NOT USE GLOBAL VARIABLES in any question.

You MUST NOT USE NESTED FUNCTIONS in any question.

You MUST NOT USE eval$()$ function in any question.

You MUST NOT USE ITERATION AT ALL $($No$,$ for or while loops, no iterating over a list or string, No list or dictionary comprehensions, $..$etc$)$

Problem Statement

The directory structure is represented as a nested string with the following format:

Directories: Represented as dir$\_$name$[$contents$],$ where contents can include files or other directories.

Files: Represented as file$\_$name$($size$)$ where size is an integer denoting the file size.

Contents: Multiple files and$/$or directories are separated by commas.

Note: The file and directory names CAN be different in test cases, you should not assume the the filenames or directory names to be always "file$1"$ or "fileA", your solution should work for the general case independent of file names and directory names.

The goal is to implement recursive functions to:

Count the total number of files.

Calculate the total size of all files.

Find the largest file in the directory.

Functionality

Part a: Count Files

Implement a function count$\_$files$($directory$)$ to count the total number of files in the directory structure.

Example Usage:

# Input directory $=$ "root$[$file$1(10),$file$2(20),$subdir$1[$file$3(15),$subdir$2[$file$4(25),$file$5(30)]]]"$ # Output print$($count$\_$files$($directory$))$ # Output: $5$

Part b: Sum File Sizes

Extend the functionality to calculate the total size of all files. Implement the function sum$\_$file$\_$sizes$($directory$).$

Example Usage:

# Input directory $=$ "Documents$[$myFile$(10),$file$2(20),$files$[$file$3(15),$subdir$[$file$4(25),$file$5(30)]]]"$ # Output print$($sum$\_$file$\_$sizes$($directory$))$ # Output: $100$

Part c: Largest File

Add functionality to find the largest file in the directory structure. Implement the function largest$\_$file$($directory$).$

Example Usage:

# Input directory $=$ "main$[$fileA$(10),$fileB$(20),$subdirA$[$fileC$(15),$subdirB$[$fileD$(25),$fileE$(30)]]]"$ # Output print$($largest$\_$file$($directory$))$ # Output: "fileE"

Constraints

You MUST USE RECURSION in all parts.

Each part must include at least one helper function.

No use of regular expressions or external libraries for parsing is allowed.

Assume the input string is well$-$formed and free of invalid characters.

Implementation Details

Parsing the Directory Structure

Directories are enclosed in $[$ and $].$

Files are enclosed in $($ and $).$

Recursive parsing is required to handle nested directories.

Helper Functions

Use helper functions to extract components $($files or directories$)$ from within a directory.

Implement recursion to process nested directories.

Function Descriptions

count$\_$files$($directory$)$

Traverses the directory structure recursively.

Counts all files, including those in nested directories.

sum$\_$file$\_$sizes$($directory$)$

Traverses the directory structure recursively.

Sums up the sizes of all files.

largest$\_$file$($directory$)$

Traverses the directory structure recursively.

Tracks the largest file encountered and its size.

Example Directory Structures

Example $1$:

Input:

root$[$file$1(10),$file$2(20),$subdir$1[$file$3(15),$subdir$2[$file$4(25),$file$5(30)]]]$

Output:

count$\_$files$($directory$)->5$ sum$\_$file$\_$sizes$($directory$)->100$ largest$\_$file$($directory$)->$ "file$5"$

Example $2$:

Input:

main$[$fileA$(5),$subdir$[$fileB$(10),$fileC$(20)]]$

Output:

count$\_$files$($directory$)->3$ sum$\_$file$\_$sizes$($directory$)->35$ largest$\_$file$($directory$)->$ "fileC"

Testing

To test the solution, use the provided example directory structures or create custom inputs. Ensure that the recursive logic correctly handles deeply nested directories and varying file sizes.