Cheatsheets for CM1035 Algorithms & Data Structures 1 (#25)

* init directory
* add Pseudocode syntax
* add section on vectors
* add section on queues
* seperate general syntax from data structures
* add section on stacks
* explicitly construct structures
* unify documents, update README
* generate PDF
* add section on time complexity
* update chart price
* update README

level-4/algorithms-and-data-structures-i/student-notes/fabio-lama/README.md

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+# About
+
+Listed here is a collection of cheatsheet by topic. Those cheatsheets do not
+explain the topics in depth, but rather serve as quick lookup documents.
+Therefore, the course material provided by the lecturer should still be studied
+and understood. Not everything that is tested at the mid-terms or final exams is
+covered and the Author does not guarantee that the cheatsheets are free of
+errors.
+
+* [Pseudocode, Data Structures & Time
+  Complexity](./cheatsheet_pseudocode_data_structures.pdf)
+
+# Building
+
+_NOTE_: This step is only necessary if you chose to modify the base documents.
+
+The base documents are written in [AsciiDoc](https://asciidoc.org/) and can be
+found in the `src/` directory.
+
+The following dependencies must be installed (Ubuntu):
+
+```console
+$ apt install -y ruby-dev wkhtmltopdf
+$ gem install asciidoctor
+$ chmod +x build.sh
+```
+
+To build the documents (PDF version):
+
+```console
+$ ./build.sh pdf
+```
+
+Optionally, for the HTML version:
+
+```console
+$ ./build.sh html
+```
+
+and for the PNG version:
+
+```console
+$ ./build.sh png
+```
+
+The generated output can be deleted with `./build.sh clean`.
+
+# Disclaimer
+
+The Presented Documents ("cheatsheets") by the Author ("Fabio Lama") are
+summaries of specific topics. The term "cheatsheet" implies that the Presented
+Documents are intended to be used as learning aids or as references for
+practicing and does not imply that the Presented Documents should be used for
+inappropriate practices during exams such as cheating or other offenses.
+
+The Presented Documents are heavily based on the learning material provided by
+the University of London, respectively the VLeBooks Collection database in the
+Online Library and the material provided on the Coursera platform.
+
+The Presented Documents may incorporate direct or indirect definitions,
+examples, descriptions, graphs, sentences and/or other content used in those
+provided materials. **At no point does the Author present the work or ideas
+incorporated in the Presented Documents as their own.**

level-4/algorithms-and-data-structures-i/student-notes/fabio-lama/build.sh

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+#!/bin/bash
+
+# Because `make` sucks.
+
+gen_html() {
+    # Remove suffix and prefix
+    FILE=$1
+    OUT=${FILE%.adoc}
+    HTML_OUT="cheatsheet_${OUT}.html"
+
+    asciidoctor $FILE -o ${HTML_OUT}
+}
+
+# Change directory to src/ in order to have images included correctly.
+cd "$(dirname "$0")/src/"
+
+case $1 in
+    html)
+        for FILE in *.adoc
+        do
+            # Generate HTML file.
+            gen_html ${FILE}
+        done
+
+        # Move up from src/
+        mv *.html ../
+        ;;
+    pdf)
+        for FILE in *.adoc
+        do
+            # Generate HTML file.
+            gen_html ${FILE}
+
+            # Convert HTML to PDF.
+            PDF_OUT="cheatsheet_${OUT}.pdf"
+            wkhtmltopdf \
+                --enable-local-file-access \
+                --javascript-delay 2000\
+                $HTML_OUT $PDF_OUT
+        done
+
+        # Move up from src/
+        mv *.pdf ../
+
+        # Cleanup temporarily generated HTML files.
+        rm *.html > /dev/null 2>&1
+        ;;
+    png | img)
+        for FILE in *.adoc
+        do
+            # Generate HTML file.
+            gen_html ${FILE}
+
+            # Convert HTML to PNG.
+            IMG_OUT="cheatsheet_${OUT}.png"
+            wkhtmltopdf \
+                --enable-local-file-access \
+                --javascript-delay 2000\
+                $HTML_OUT $IMG_OUT
+        done
+
+        # Move up from src/
+        mv *.png ../
+
+        # Cleanup temporarily generated HTML files.
+        rm *.html > /dev/null 2>&1
+        ;;
+    clean)
+        rm *.html > /dev/null 2>&1
+        rm *.png > /dev/null 2>&1
+        rm ../*.html > /dev/null 2>&1
+        rm ../*.png > /dev/null 2>&1
+        ;;
+    *)
+        echo "Unrecognized command"
+        ;;
+esac

level-4/algorithms-and-data-structures-i/student-notes/fabio-lama/src/pseudocode_data_structures.adoc

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+= Cheatsheet - Pseudocode, Data Structures & Time Complexity
+Fabio Lama <fabio[email protected]>
+:description: Module: CM1015 Computational Mathematics, started 04. April 2022
+:doctype: article
+:sectnums: 4
+:toclevels: 4
+:stem:
+
+== General Pseudocode Syntax (Example)
+
+Pseudocode describes the logical steps of an algorithm or process in
+(mostly) plain language.
+
+image::assets/morning_chart.png[width=550, float="right"]
+
+. stem:[bb "function " "Morning"(tt "conscious, done, cereal")]
+. stem:["    " bb "if " tt "conscious" = "TRUE" bb " then"]
+. stem:["    " "    " tt "maths" larr 0]
+. stem:["    " "    " bb "for " 1 <= i <= tt "done" bb " do"]
+. stem:["    " "    " "    " tt "maths" larr tt "maths" + 1]
+. stem:["    " "    " bb "end for"]
+. stem:["    " "    " bb "while " tt "cereal" > 0 bb " do"]
+. stem:["    " "    " "    " tt "cereal" larr tt "cereal" - 1]
+. stem:["    " "    " bb "end while"]
+. stem:["    " bb "end if"]
+. stem:["    " bb "return " "ready!"]
+. stem:[bb "end function"]
+
+We can now call the stem:["Morning"] function:
+
+. stem:[tt "status" larr "Morning"("TRUE", 10, 5)]
+
+== Data Structures
+
+=== Vector
+
+A **vector** is a sequentially orderer collection of elements (like an ordered
+set). For example, the following vector stem:[v] is of size _three_ and
+contains the elements stem:[A], stem:[B] and stem:[C]:
+
+[stem]
+++++
+"new Vector " v(3) = (A, B, C)
+++++
+
+The size of the vector is **fixed**, meaning one cannot add or remove items from
+it (only replace individual items).
+
+NOTE: In some programming languages, "vector" refers to a _growable_ collection
+of data, which is very different and not the case here.
+
+==== Operations
+
+We can do operations on vectors:
+
+* stem:["LENGTH"\[v\]]: Returns the size of vector stem:[v].
+* stem:[v\[k\]]: Returns the element of the vector stem:[v] at index
+stem:[k].
+* stem:[v\[k\] larr o]: Stores the element stem:[o] into the vector stem:[v]
+at index stem:[k].
+
+For example, given vector:
+
+[stem]
+++++
+"new Vector " v(4) = (A, B, C, D)
+++++
+
+Then:
+
+[stem]
+++++
+"LENGTH"[v] = 4\
+v[2] = B\
+v[2] larr Z\
+v[2] = Z\
+v = (A, Z, C, D)
+++++
+
+NOTE: In programming languages, the index usually starts at stem:[0],
+respectively the first element of the set is indexed at stem:[0], followed by
+stem:[1, 2, ...]. In our case, we start the index at stem:[1].
+
+=== Queue
+
+A **queue** is a data structure where elements need to "wait" before they get
+processed. Elements the get processed in the order the elements were added,
+respectively "first in first out" (FIFO). Queues are not fixed sized. Elements
+get added to the "tail" and come out at the "head".
+
+[stem]
+++++
+"new Queue " q = (A, B, C)
+++++
+
+==== Operations
+
+We can do operations on queues:
+
+* stem:["HEAD"\[q\]]: Returns the element at the head of the queue.
+* stem:["DEQUEUE"\[q\]]: Returns the element at the head of the queue and removes
+that element from the queue.
+* stem:["ENQUEUE"\[o, q\]]: Adds the element stem:[o] to the tail of the queue.
+* stem:["EMPTY"\[q\]]: Returns _true_ if the queue is empty or _false_ if otherwise.
+
+For example, given queue:
+
+[stem]
+++++
+"new Queue " q = (A, B, C, D)
+++++
+
+Then:
+
+[stem]
+++++
+"HEAD"[q] = D\
+q = (A, B, C, D)\
+"DEQUEUE"[q] = D\
+q = (A, B, C)\
+"ENQUEUE"[Z, q]\
+q = (Z, A, B, C)\
+"EMPTY"[q] = "false"
+++++
+
+=== Stack
+
+A stack is like a queue, but elements are processed in the "last in first out"
+(LIFO) order.
+
+==== Operations
+
+* stem:["PUSH"\[o,s\]]: Adds element stem:[o] to the stack.
+* stem:["TOP"\[s\]]: Returns the last inserted element from the stack.
+* stem:["POP"\[s\]]: Returns the last inserted element from the stack and
+removes that element from the stack.
+* stem:["EMPTY"\[s\]]: Returns _true_ if the stack is empty or _false_ if
+otherwise.
+
+For example, given stack:
+
+[stem]
+++++
+"new Stack " s = (A, B, C)
+++++
+
+Then:
+
+[stem]
+++++
+"PUSH"[Z,s]\
+s = (A, B, C, Z)\
+"TOP"[s] = Z\
+s = (A, B, C, Z)\
+"POP"[s] = Z\
+s = (A, B, C)\
+"EMPTY"[s] = "false"
+++++
+
+== Time Complexity
+
+.Source: https://youtu.be/47GRtdHOKMg
+image::assets/time_complexity.jpg[align=center, width=500]