ruby version: Leetcode Longest Substring Without Repeating Characters

script.rb

# Leetcode: Longest Substring Without Repeating Characters 
# ---------------------------------------------------------
#
# script is an implementation of the sliding window technique to find the
# length of the longest substring without repeating characters in a given
# string.
def length_of_longest_substring(s)

  # Empty hash to store the last index of each character in the string.
  char_index = {}

  # This variable represents the starting index of the current window
  start_index = 0

  # This variable will store the length of the longest substring without repeating characters.
  max_length = 0
  
  # it will iterate over each character char in the string s along with its index index.
  s.chars.each_with_index do |char, index|

    # This line checks if the current character char is already 
    # in the hash char_index and if its last index is greater 
    # than or equal to the start_index.
    if char_index.key?(char) && char_index[char] >= start_index

      # If the condition in the previous line is true, this line updates the
      # start_index to be one more than the last index of the current character.
      # This ensures that the start_index is moved to the appropriate position
      # to exclude any repeating characters within the new window.
      start_index = char_index[char] + 1
    end
    
    # This line updates the hash char_index to store the current index of the character char.
    char_index[char] = index

    # This line updates the max_length to be the maximum of the current max_length and 
    # the length of the current window (which is index - start_index + 1).
    max_length = [max_length, index - start_index + 1].max

  end
  
  max_length
end