Decomposition and algorithm practice questions
Every programming problem needs decomposing so that it can be properly understood. From this, an algorithm can be designed and tested.
Part of
Designing an algorithm
Algorithm design option one - flow diagram
Algorithm design option two - pseudo-code
# for the purpose of this example the array starts at 1
Options ← [“paper”, “rock”, “scissors”]
OUTPUT “Please enter your choice: 1, 2, or 3:”
player_choice ← USERINPUT
comp_choice ← RANDOM_INT (1, 3)
IF player_choice = comp_choice THEN
OUTPUT “draw”
ELSE
IF player_choice = 1 THEN
IF comp_choice = 2 THEN
winner ← “player”
ELSE
winner ← “comp”
END IF
ELSE IF player_choice = 2 THEN
IF comp_choice = 3 THEN
winner ← “player”
ELSE
winner ← “comp”
END IF
ELSE IF player_choice = 3 THEN
IF comp_choice = 1 THEN
winner ← “player”
ELSE
winner ← “comp”
END IF
IF winner = “player” THEN
OUTPUT choices[player_choice] + “ beats” + choices[comp_choice]
ELSE
OUTPUT choices[comp_choice] + “ beats “ + choices[player_choice]
END IF
END IF
Testing table
Tests will be required to check that the final program runs correctly, although this will be more difficult than example one as one value is a random number. Because of the complexity of the program, validation is not included in the exam question. However, it would be expected if this was a programming project scenario.
| Test no | Description | Test data | Test type | Expected outcome |
|---|---|---|---|---|
| 1 | Both computer and player select 2 | 2 | Normal | “draw” |
| 2 | Computer selects winning choice of rock | 2 | Normal | “rock beats scissors” |
| 3 | Player selects winning choice of paper | 1 | Normal | “paper beats rock” |
| 1 | Both computer and player select 1 | 1 | Normal | “draw” |
| 2 | Computer selects winning choice of scissors | 3 | Normal | “scissors beats paper” |
| 3 | Player selects winning choice of rock | 2 | Normal | “rock beats scissors” |
The problem has now been fully decomposed and an algorithm has been designed.