Glasgow | 26-SDC-Mar | Mohammed Abdoon | Sprint 2 | Improve Code With Caches - #221
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M-Abdoon wants to merge 1 commit into
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Glasgow | 26-SDC-Mar | Mohammed Abdoon | Sprint 2 | Improve Code With Caches#221M-Abdoon wants to merge 1 commit into
M-Abdoon wants to merge 1 commit into
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M-Abdoon
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📅 Sprint 2
cjyuan
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Jul 17, 2026
Comment on lines
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| cache = {} | ||
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| def fibonacci(n): | ||
| if n in cache: | ||
| return cache[n] | ||
| if n <= 1: | ||
| return n | ||
| return fibonacci(n - 1) + fibonacci(n - 2) | ||
| result = fibonacci(n - 1) + fibonacci(n - 2) | ||
| cache[n] = result | ||
| return result |
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Code is correct.
Could you look into an approach that doesn't require keeping the cache in the global scope?
Comment on lines
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| coin = coins[0] | ||
| for count in range(total // coin + 1): | ||
| intermediate = ways_to_make_change_helper(total - coin * count, coins[1:]) | ||
| ways += intermediate | ||
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| cache[key] = ways |
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Array and tuple creations are relatively costly operations.
coins can only be one of the following 9 tuples:
(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-tuples at line 21 (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.
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