London | 25-SDC-July | Fatma Arslantas | Sprint 2 | Improve code with caches

[AFatmaa]

Learners, PR Template

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

Changelist

I improved the performance of fibonacci and making_change functions using caching (memoisation).

• Fibonacci:
  • I added a memo dictionary to store calculated results.
  • This stops the code from calculating the same numbers again.
• Making Change:
  • I added a global cache dictionary using tuple keys.
  • I added a specific check (if len(coins) == 1) to solve the problem with math instead of looping.

Questions

I don’t have any questions, thank you!

[cjyuan]

Better to make cache local inside ways_to_make_change(), and define
ways_to_make_change_helper() as an inner function inside ways_to_make_change().

Since that's not the purpose of this exercise, change is optional.

[cjyuan]

From line 45, we know coins can only be one of the following 9 lists:

[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-lists at line 45, and
• create key as (total, a_value_identifiying_one_of_the_sublists) instead of as (total, tuple(coins))

I don't think this exercise expects trainees to optimize the code to this level. So change is optional.