Algorithms – Fundamentals

This post is a term explanation for algorithm fundamentals – including IHK key points, examples, and exam questions.

In a Nutshell

An algorithm is a clear, finite set of instructions that leads step by step from an initial state to a target state.

Properties (MUST-HAVE)

1. Uniqueness / Determinacy
2. Executability / Effectiveness
3. Finiteness (Termination)
4. Determinism (in the classical exam context)
5. Generality (for a problem class)

Algorithmic Building Blocks (very exam-relevant)

Every algorithm can be reduced to three structures – basis for Nassi-Shneiderman diagrams:

Sequence

a = 5
b = 10
summe = a + b

Selection

IF age >= 18 THEN
  canVote = true
ELSE
  canVote = false

Iteration

WHILE counter < 10
  print("Hello")
  counter = counter + 1

Description Methods

• Flowchart
• Nassi-Shneiderman diagram (very IHK-relevant)
• Pseudocode
• Program code

Examples You Should Know

• Sorting: BubbleSort, QuickSort
• Searching: linear search, binary search (only on sorted data)

Typical Exam Questions (with Short Answer)

1. What are the three basic building blocks of every algorithm? Sequence, selection, iteration.
2. Why must an algorithm be finite? It must terminate – infinite loops are not a valid solution.
3. When can binary search be applied? Only with sorted data.

Tip for the IHK

Practice Nassi-Shneiderman diagrams for:

• largest number in list
• even/odd
• sum 1..n
• BubbleSort for a small list