Glasgow | Prati Amalden | Module Complexity | Sprint 2 | Improve with caching #66
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| count_of_coin = 0 | ||
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| while coin * count_of_coin <= total: | ||
| total_from_coins = coin * count_of_coin | ||
| intermediate = ways_to_make_change_helper(total - total_from_coins, rest) | ||
| ways += intermediate | ||
| count_of_coin += 1 | ||
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| _change_cache[key] = ways |
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Great job in identifying that we could get rid of the outer for loop.
| key = (total, coins) | ||
| if key in _change_cache: | ||
| return _change_cache[key] | ||
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| coin = coins[0] | ||
| rest = coins[1:] |
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From line 29, we could identify 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 29 (e.g. use another cache), and
- create
keyas (total, an_integer_that_map_to_the_subtuple) instead of as (total, tuple of coins)
I don't think this exercise expects trainees to optimize the code to this level. So change is optional.
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