2.2 Problem solving and programming

Question 1

What is the main difference between functions and procedures? (2.2.1)

Answer 1

Function: must always return single value

Procedure: don’t have to

Question 2

What does the divide and conquer stage entail? (2.2.2)

Answer 2

• Divide: half problem size every iteration
• Conquer: each subproblem recursively solved
• Merge: subproblem solutions recombined
• Simplifies complex problems quickly

Question 3

What does the problem recognition stage entail? (2.2.2)

Answer 3

• Stakeholder states solution requirements
• Information clearly defines problem & system requirements
• Definable by:
• Current solution strengths / weaknesses
• Inputs / outputs / stored data

Question 4

What are heuristics? (2.2.2)

Answer 4

• Non-optimal, ‘rule-of-thumb’
• Approximate solution when standard too long to find
• Not perfectly accurate / complete

Question 5

What are local and global variables? (2.2.1)

Answer 5

Local:

• Only accessible within own subroutine
• Deleted upon subroutine end
• Ensures self-containment

Global:

• Accessed across whole program
• Useful for use by multiple parts
• Unintentional editing risk
• Exists until program termination, uses memory

Question 6

What does the problem decomposition stage entail? (2.2.2)

Answer 6

• Problem broken into small problems
• Each subproblem representable as self-contained subroutine
• Reduces problem complexity
• Enables reusable component recognition
• Team division easier
• Individual design / development / testing
• Parallel module development, faster delivery

Question 7

What is modular programming? (2.2.1)

Answer 7

• Splitting large complex programs 🡆 smaller self-contained modules
• Easier task division between team
• Simplifies testing / maintenance, individuality
• Improves component reusability

Question 8

What is performance modelling? (2.2.2)

Answer 8

• Testing various loads mathematically on different OSs
• Cheaper, less time-consuming, safer testing method, where trial run
  unfeasible

Question 9

What is data mining? (2.2.2)

Answer 9

• Identifying patterns / outliers in large data sets
• Collected from various sources (big data)
• Spot trends / correlations not immediately obvious
• Insights aid future predictions

Question 10

What is backtracking? (2.2.2)

Answer 10

• Methodically builds solution based on correct visited paths
• Invalid path finding 🡆 backtracking to previous stage

Question 11

What is the difference between passing by value and passing by reference?
(2.2.1)

Answer 11

By value:

• Copy of value passed, discarded at end
• Value outside subroutine unaffected

By reference:

• Parameter address given
• Value updated at given address

Question 12

What is recursion, and what are its advantages / disadvantages? (2.2.1)

Answer 12

Subroutine calling itself in execution, continues until stopping condition met.

Advantages:

• Representable in fewer lines
• Easier expression

Disadvantages:

• Stack overflow (memory depletion)
• Difficult tracing

Question 13

What makes a problem solvable by computational methods? (2.2.2)

Answer 13

Solved using algorithms, not impractical resource / time usage

Question 14

What is an IDE and what main features does it provide? (2.2.1)

Answer 14

What: Program providing tool set easing writing, development & debugging

Features:

• Stepping (single-line execution, monitoring effect)
• Variable watch (observing contents real-time)
• Breakpoint (setting stop in program)
• Source code editor (autocompletion, indentation, syntax highlighting)
• Debugging tools (run-time error detection)