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|
def assert_equal(x, y)
if x == y
puts 'PASS!'
else
puts "FAIL!: expected `#{x.inspect}` got `#{y.inspect}`"
end
end
=begin
x
|a|b|c|d|e|f|
y
|a|*|d|*|f|
=end
class Solution
def self.run(sequence, pattern)
p = 0
index = nil
0.upto(sequence.length - 1) do |n|
x = sequence[n]
y = pattern[p]
if y == '*'
index = n if p.zero?
l = pattern[p + 1]
p += 2 if l == x
elsif x == y
index = n if p.zero?
p += 1
else
index = nil unless p >= pattern.size
p = 0
end
end
index
end
class Input
attr_reader :position
def initialize(string)
@string = string
@position = 0
end
def seek(position)
@position = position
end
def previous
@string.chars[position - 1]
end
def current
@string.chars[position]
end
def peek
@string.chars[position + 1]
end
def advance(n)
@position += n
end
def eos?
@position == @string.size
end
end
class Atom
attr_accessor :next
def parse(string)
match?(Input.new(string))
end
def match_next?(input)
self.next.match?(input)
end
def to_s
self.class.to_s
end
def inspect
"#{self}->#{self.next&.inspect}"
end
end
class Start < Atom
def match?(input)
result = nil
until input.eos?
result = input.position
break if match_next?(input)
input.seek(result + 1)
result = nil
end
result
end
def to_s
"start"
end
end
class Wildcard < Atom
def initialize(lookahead)
@lookahead = lookahead
end
def match?(input)
return true if input.eos?
if input.peek == @lookahead
input.advance(1)
match_next?(input)
else
input.advance(1)
match?(input)
end
end
def to_s
"*"
end
end
class Final < Atom
def match?(*)
true
end
def to_s
"final"
end
end
class Literal < Atom
attr_reader :value
def initialize(value)
@value = value
end
def match?(input)
if value == input.current
input.advance(1)
match_next?(input)
else
false
end
end
def to_s
@value
end
end
def self.build_machine(pattern)
initial = Start.new
machine = initial
for i in 0...pattern.size
atom = case pattern[i]
when '*'
Wildcard.new(pattern[i + 1])
else
Literal.new(pattern[i])
end
machine.next = atom
machine = atom
end
machine.next = Final.new
initial
end
def self.run(sequence, pattern)
machine = build_machine(pattern)
machine.parse(sequence)
end
def self.state_for(token)
return :final if token.nil?
case token
when '*'
:wildcard
else
:literal
end
end
def self.debug(state, sequence_pos, pattern_pos, sequence, pattern)
return unless ENV['DEBUG']
puts [state].inspect
puts " " + (" " * sequence_pos) + "v"
puts " " + sequence
puts " " + (" " * pattern_pos) + "v"
puts " " + pattern
end
# start, literal, wildcard, final
def self.run(sequence, pattern)
state = :start
sequence_pos = 0
pattern_pos = 0
result = nil
while pattern_pos < pattern.size && sequence_pos < sequence.size
debug(state, sequence_pos, pattern_pos, sequence, pattern)
case state
when :start
pattern_pos = 0
result = sequence_pos
state = state_for(pattern[pattern_pos])
when :literal
if sequence[sequence_pos] == pattern[pattern_pos]
pattern_pos += 1
state = state_for(pattern[pattern_pos])
else
state = :start
result = nil
end
sequence_pos += 1
when :wildcard
lookahead = pattern[pattern_pos + 1]
if sequence[sequence_pos] == lookahead
state = state_for(lookahead)
pattern_pos += 1
else
sequence_pos += 1
end
when :final
break
end
end
result
end
def self.run(sequence, pattern, index = 0)
puts [sequence, pattern, index].inspect if ENV['DEBUG']
return index if pattern.nil? || pattern.empty?
return index if sequence.nil? || sequence.empty?
case (atom = pattern[0])
when '*'
if sequence[1] == pattern[1]
run(sequence[1..-1], pattern[1..-1], index)
else
run(sequence[1..-1], pattern, index)
end
else
if sequence[0] == atom
run(sequence[1..-1], pattern[1..-1], index)
else
run(sequence[1..-1], pattern, index + 1)
end
end
end
def self.run(sequence, pattern, index = 0)
return index if pattern.empty?
return index if sequence.empty?
atom = pattern[0]
if atom != '*'
if sequence[0] == atom
run(sequence[1..-1], pattern[1..-1], index)
else
run(sequence[1..-1], pattern, index + 1)
end
else
if sequence[1] == pattern[1]
run(sequence[1..-1], pattern[1..-1], index)
else
run(sequence[1..-1], pattern, index)
end
end
end
end
=begin
x
|a|b|c|d|e|f|
y
|a|*|d|*|f|
=end
assert_equal 0, Solution.run('abcdef', 'a*d*f')
assert_equal 0, Solution.run('abcdefg', 'a*d*f')
assert_equal 0, Solution.run('abcdefxyz', 'a*d*f')
assert_equal 0, Solution.run('mo is the best', 'm* is the ****')
assert_equal 1, Solution.run('abcd', 'b*d')
assert_equal 1, Solution.run('abcddef', 'bc*de')
assert_equal 2, Solution.run('abacd', 'ac*')
assert_equal 3, Solution.run('xyzabcdef', 'a*d*f')
assert_equal 7, Solution.run('Phone: +1(403)-555-5555', '+*(***)-***-****')
|
