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#!/usr/bin/ruby
#
# See ../README.md
#
#
# Run as: ruby ch-2.rb < input-file
#
#
# Recursively count matches:
# - If either the string or the pattern is empty, there are no matches.
# - Else, + count the matches if we don't match at the first character
# if the string.
# + if the first character of the string equals the first
# character of the pattern:
# o add 1 if the pattern is just one character long
# o else, add the number of matches starting from the
# then next character in the string, and the next
# character in the pattern.
#
def matches (string, pattern)
if string . length == 0 || pattern . length == 0
return 0
end
count = matches string [1 .. -1], pattern
if string [0] == pattern [0]
if pattern . length == 1
count += 1
else
count += matches string [1 .. -1], pattern [1 .. -1]
end
end
return count
end
ARGF . each_line do |_|
(string, pattern) = _ . strip . split
puts matches string, pattern
end
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