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35 lines
1.2 KiB
Ruby
35 lines
1.2 KiB
Ruby
# You are a product manager and currently leading a team to develop a new product.
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# Unfortunately, the latest version of your product fails the quality check.
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# Since each version is developed based on the previous version,
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# all the versions after a bad version are also bad.
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#
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# Suppose you have n versions [1, 2, ..., n] and you want to find out the first bad one,
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# which causes all the following ones to be bad.
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#
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# You are given an API bool is_bad_version?(version) which will return whether version is bad.
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# Implement a function to find the first bad version.
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# You should minimize the number of calls to the API.
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# The is_bad_version? API is already defined for you.
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# @param {Integer} version
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# @return {boolean} whether the version is bad
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# def is_bad_version?(version)
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# version >= 69 ? true : false
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# end
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# @param {Integer[]} versions
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# @return {Integer}
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def first_bad_version(versions)
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# binary search
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midpoint = (versions.length - 1) / 2
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middle_version = versions[midpoint]
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return 1 if middle_version == versions.first
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if is_bad_version?(middle_version)
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first_bad_version(versions[0..midpoint])
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else
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midpoint + first_bad_version(versions[midpoint..-1])
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end
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end
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