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London | 26-Jul-SDC | Roman Sanaye | Sprint 2 | Improve Code with Caches - #249
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RomanSanaye
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| def fibonacci(n): | ||
| if n <= 1: | ||
| return n | ||
| return fibonacci(n - 1) + fibonacci(n - 2) | ||
| # Initialize the cache dictionary | ||
| cache = {} |
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The cached values of this function could be reused between function calls. You could consider using function attribute instead.
Change is optional.
Comment on lines
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| @@ -26,7 +35,10 @@ def ways_to_make_change_helper(total: int, coins: List[int]) -> int: | |||
| if total_from_coins == total: | |||
| ways += 1 | |||
| else: | |||
| intermediate = ways_to_make_change_helper(total - total_from_coins, coins=coins[coin_index+1:]) | |||
| intermediate = ways_to_make_change_helper(total - total_from_coins, coins=coins[coin_index+1:], cache=cache) | |||
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Array and tuple creations are relatively costly operations.
From lines 30 and 38, we know 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 38 (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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Hi @cjyuan , |
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Task code
CYF-1182
Changelist
Implemented caching (memoization) for the ways_to_make_change solution.
(total, tuple(coins))as the cache key.