# ---------------------------------------------------------
# Compress: turn "aaabbcccc" into "a3b2c4"
# This is run-length encoding (RLE)
# ---------------------------------------------------------
def compress(s)
return "" if s.empty? # Edge case: empty string
out = [] # Result string (array for efficiency)
count = 1 # Count of repeated characters
# Start from index 1 and compare with previous charactera
(1..s.length).each do |i|
# If still repeating the same character, increase count
if i < s.length && s[i] == s[i - 1]
count += 1
else
# Character changed OR reached end of string
out << s[i - 1] # Add the character
out << count.to_s # Add how many times it repeated
count = 1 # Reset counter
end
end
out.join
end
# ---------------------------------------------------------
# Decompress: turn "a3b2c4" into "aaabbcccc"
# Reads a letter, then reads digits, expands them.
# ---------------------------------------------------------
def decompress(s)
out = [] # Result string
current_char = nil # The character being processed
number = "" # Digits representing the count
s.each_char do |c|
if c =~ /[A-Za-z]/ # Found a letter
# If we already have a previous letter + number, expand it
if current_char && !number.empty?
out << current_char * number.to_i
end
current_char = c # Start new character
number = "" # Reset number buffer
elsif c =~ /\d/ # Found a digit
number << c # Build multi-digit number
end
end
# Handle the last character + number pair
if current_char && !number.empty?
out << current_char * number.to_i
end
out.join
end
def main
s = "wwwwwwwwwwwwbwwwwwwwwwwbbbwwwwwwccccwwwwwwwwwwww"
c = compress(s)
d = decompress(c)
puts "Original: #{s}"
puts "Compressed: #{c}"
puts "Decompressed: #{d}"
end
main
=begin
run:
Original: wwwwwwwwwwwwbwwwwwwwwwwbbbwwwwwwccccwwwwwwwwwwww
Compressed: w12b1w10b3w6c4w12
Decompressed: wwwwwwwwwwwwbwwwwwwwwwwbbbwwwwwwccccwwwwwwwwwwww
=end
