[Fithi-Teklom]

Self checklist

• I have titled my PR with Region | Cohort | FirstName LastName | Sprint | Assignment Title
• My changes meet the requirements of the task
• I have tested my changes
• My changes follow the style guide

Task code

CYF-1182

Changelist

Complete Fabonacci and Making improvement with cache exercise.

[cjyuan]

Array and tuple creations are relatively costly operations.

We could observe that coins can only be one of the following 9 arrays:

[200, 100, 50, 20, 10, 5, 2, 1]
[100, 50, 20, 10, 5, 2, 1]
[50, 20, 10, 5, 2, 1]
...
[1]
[]

We could further improve the performance if we can

• avoid repeatedly creating the same sub-arrays at line 37 (e.g. use another cache), and
• create key as (total, a_unique_integer_identifying_the_subarray) instead of as (total, tuple of coins)
  • There are only a small number of different subarrays. We can easily assign each subarray a unique integer.

[cjyuan]

• We could also pass both the list and coin_list_id to the helper function. This way, we could keep the coin list local and make the helper reusable for different coin list.

• We could also rename coin_list_id and use it as the starting index of the sub list, and modify the loop (and few conditions) to iterate through the sub list. This way, we don't need to allocate additional space on lines 4-9.

[cjyuan]

Changes look good.