Space - Stephanie #28
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CheezItMan
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CheezItMan
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Your solutions mostly work but have less than ideal time complexity. Think about how you can use a hash to solve them.
Take a look at my comments and let me know if you have any questions.
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| def intersection(list1, list2) | |||
| raise NotImplementedError, "Intersection not implemented" | |||
| intersect = list1 & list2 | |||
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That works as it uses a feature of Ruby. Do think about how you'd solve it with a hash.
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| letter_hash = {} | ||
| string.chars.map do |char| | ||
| letter_hash["#{char}"] = string.count(char) |
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string.count(char) is an O(n) operation, so that makes this a total of O(n^2) operation.
It could be better doing this:
| letter_hash["#{char}"] = string.count(char) | |
| letter_hash["#{char}"] = letter_hash["#{char}"].nil? ? 1 : letter_hash["#{char}"] + 1 |
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| def palindrome_permutation?(string) | |||
| return false if string1.length != string2.length | ||
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| string1.chars.each do |char| | ||
| if string2.include?(char) |
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.include? is an O(n) operation, making this an O(n^2) method. Can you think of a better way to do this with a hash?
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| def permutations?(string1, string2) | |||
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This fails for heelo and hello, and it's more than a little inefficient.
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