01 prework methodical problem solving #1
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time - o(n^2)? space - o(1)?
time - o(n). space - o(1)?
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| @staticmethod | ||
| def test(): | ||
| phrases = [ |
| # overall | ||
| # time - o(n) | ||
| # space - o(n) | ||
| # where n is the length of `phrase` |
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Is this o(n) total or o(n) not including the input?
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@robot-dreams my understanding is o(n) total where n is length of phrase because a larger phrase may result in a larger set. (eg: 500-character phrase where each char is unique takes up more space than a 10-character phrase where each char is unique)
| # * since c is a temporary variable | ||
| for c in phrase: | ||
| # o(1) constant time and space? | ||
| # does set.discard take constant time and space? |
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Yes, we can assume this (we'll talk in more detail about how set works in a later session)
| reached before the phrase ends | ||
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| The only difference from is_pangram_1 is that `len(alpha) == 0` becomes | ||
| `alpha == set()` |
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One more alternative you might consider here is not alpha
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@robot-dreams ah I see! I'm still not very clear on what counts as falsey for not so I wanted to be more explicit. I don't program in Python on a daily basis - it's just the language I use for DS&A since there are the most resources for it. so i'm teaching myself python along the way XD
| # not sure about time and space. | ||
| # time - o(n)? | ||
| # * is length of the set calculated everytime or is it stored in a | ||
| # variable somewhere? |
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Good question! You can assume it'll be stored.
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@robot-dreams if that's so, then len(alpha) is o(1) yes?
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| # overall loop | ||
| # time - o(n^2)? | ||
| # * o(n) `for c in phrase` | ||
| # * within that, another o(n) for `len(alpha)`? |
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What's the overall time if len(alpha) is o(1)?
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@robot-dreams if len(alpha) is o(1), then overall time is o(n) where n is length of phrase. max one iteration through phrase in for c in phrase
prework for the first class - methodical problem solving