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https://github.com/TheAlgorithms/Ruby
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45 lines
No EOL
1 KiB
Ruby
45 lines
No EOL
1 KiB
Ruby
# Challenge name: Valid Palindrome
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#
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# Given a string s, determine if it is a palindrome,
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# considering only alphanumeric characters and ignoring cases.
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#
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# Example 1:
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# Input: s = "A man, a plan, a canal: Panama"
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# Output: true
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# Explanation: "amanaplanacanalpanama" is a palindrome.
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#
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# Example 2:
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# Input: s = "race a car"
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# Output: false
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# Explanation: "raceacar" is not a palindrome.
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#
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# Constraints:
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# 1 <= s.length <= 2 * 105
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# s consists only of printable ASCII characters.
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# @param {String} s
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# @return {Boolean}
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#
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# Approach 1: Using Ruby method .reverse
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#
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# Time Complexity: O(n)
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#
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def is_palindrome(s)
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letters_only = s.downcase.gsub(/[^0-9a-z]/i, '')
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letters_only.reverse == letters_only
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end
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s = 'A man, a plan, a canal: Panama'
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puts is_palindrome(s)
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# Output: true
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# Explanation: "amanaplanacanalpanama" is a palindrome.
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s = 'race a car'
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puts is_palindrome(s)
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# Output: false
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# Explanation: "raceacar" is not a palindrome.
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s = 'ab_a'
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puts is_palindrome(s)
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# Output: true
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# Explanation: "aba" is a palindrome. |