book-store: Add test that requires use of both groups of 4 and groups of 5 #1620
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cmccandless
changed the title
cmccandless
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Nov 24, 2019
| "description": "Two groups of four and a group of five", | ||
| "comments": ["Suggested grouping, [[1,2,3,4],[1,2,3,5],[1,2,3,4,5]]. Solutions can pass all the other tests if they just try to group without using any groups of 5. This test case breaks that since it requires both 4-groups and 5-groups."], | ||
| "input": { | ||
| "basket": [1,1,1,2,2,2,3,3,3,4,4,5,5] |
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As mentioned in my comment here, I would suggest shuffling the input numbers here (or adding an additional case that has the inputs shuffled), as this ensures a more robust solution.
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Good point, I've added a second test to check for that.
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Yeah that's brilliant idea to add test book store that gives in shuffled order |
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I agree with adding this, but I've tended to consider an omitted test (as opposed to an included test that was manifestly wrong) as blocked by #1560 ... should this one also get a Hold label for the moment? Not that I want to add to the backlog. |
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@sswingle Are you still interested in working on this PR? |
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Many of the "brute force" solutions I see do something like run a greedy solver multiple times with different maximum group sizes. This allows them to solve test cases that check for finding 2 groups of 4 instead of a group of 5 and a group of 3.
However, this wouldn't solve cases where you need to use both groups of 5 and groups of 4. For example, consider books = [1, 2, 3, 4, 5, 1, 2, 3, 4, 5, 1, 2, 3]. The cheapest price possible is achieved by splitting it into 1 group of 5 and 2 groups of 4, with cost = 800*(150.75 + 240.8) = 8120. Solutions like those described above will typically split it into 2 groups of 5 and 1 group of 3, with a cost of 800*(250.75 + 130.9) = 8160.
For further motivation and discussion see: exercism/python#2141