Form 4 - Computer

2024-2025

Floor 4 - Computer Room

Mr. Peter

While Loop & List

Santa Rosa de Lima English Secondary School

聖羅撒英文中學

Colégio de Santa Rosa de Lima - Secção Inglesa

Outline

List

1.

How to process List in While Loop

2.

Focusing on the List processing in looping

Python List implementation

3.

Define while loop statement for List scanning

What is List?

What is List?

0

1

...

[

]

2

1

4

1

1

1

3

1

boxes = 

In Python:

Get variable from List

list[ position ]

What is List?

0

a

"

"

2

c

4

e

1

b

3

d

text = 

We can also get letter from text

Get letter from text

text[ position ]

Python List Exercises

Python List - Ex01

Limit Particle Speeds

1.

Save your file as "ClassNumber_YourName_Ex01.py"

In a physics experiment, a sensor records particle speeds (in m/s) in a list. To avoid equipment damage, speeds exceeding a maximum threshold must be capped at that threshold. Using a while loop, modify the list so that any speed greater than the threshold is replaced with the threshold value.

2

3

Use a while loop to iterate through the numbers.

1

Iterate through each number in the speeds array and if it exceeds max_speed, replace the value with 10.

Print the final list.

Python List - Ex01

Limit Particle Speeds

1.

Save your file as "ClassNumber_YourName_Ex01.py"

In a physics experiment, a sensor records particle speeds (in m/s) in a list. To avoid equipment damage, speeds exceeding a maximum threshold must be capped at that threshold. Using a while loop, modify the list so that any speed greater than the threshold is replaced with the threshold value.

2

3

Use a while loop to iterate through the numbers.

1

Iterate through each number in the speeds array and if it exceeds max_speed, replace the value with 10.

Print the final list.

Python List - Ex02

Detect Repeated DNA Sequence

1.

Save your file as "ClassNumber_YourName_Ex02.py"

In bioinformatics, scientists analyze DNA sequences to identify repeated patterns that might indicate genetic anomalies. Given a list of integers representing short DNA segment codes (e.g., nucleotide counts), use a while loop to find and print the first repeated segment code. If no repeats exist, no need to print.

2

3

Use a while loop to iterate through the numbers.

1

Detect duplicate elements within a list using efficient validation.

Print the duplicated number

Python List - Ex02

Detect Repeated DNA Sequence

1.

Save your file as "ClassNumber_YourName_Ex02.py"

In bioinformatics, scientists analyze DNA sequences to identify repeated patterns that might indicate genetic anomalies. Given a list of integers representing short DNA segment codes (e.g., nucleotide counts), use a while loop to find and print the first repeated segment code. If no repeats exist, no need to print.

2

3

Use a while loop to iterate through the numbers.

1

Detect duplicate elements within a list using efficient validation.

Print the duplicated number

Python List - Ex03

Coffee Shop Discounts

1.

Save your file as "ClassNumber_YourName_Ex03.py"

A coffee shop offers a discount if two items on the menu add up to a specific total price (in cents). Given a list of item prices and a target total, find the indices of two items that qualify for the discount.

2

3

Use a while loop to iterate through the prices.

1

Use a second while loop to check pairs (inner loop).

Check and find two distinct items summing to the target 

4

Print the result