Merge pull request neetcode-gh#2016 from MikeQCarr/longest-consecutiv…

…e-sequence

Update: 0128-longest-consecutive-sequence.rb

ruby/0128-longest-consecutive-sequence.rb

@@ -1,52 +1,14 @@
 def longest_consecutive(nums)
- return 0 if nums.empty?
-
- hash = {}
- nums.each { |num| hash[num] = true }
- longest = 0
- nums.each do |num|
- next if hash[num - 1]
-
- challenger = 1
- loop do
- if hash[num + challenger]
- challenger += 1
- else
- break
- end
- end
- longest = challenger if challenger > longest
- end
-
- longest
-end
-
-# Another way to do it.
-def longest_consecutive(nums)
- return 0 if nums.empty?
-
- hash = {}
- nums.each { |num| hash[num] = -1 }
- nums.each do |num|
- next unless hash[num] == -1
-
- longest_consec = 1
- loop do
- val = hash[num + longest_consec]
- case val
- when -1
- hash[num + longest_consec] = -2
- longest_consec += 1
- when nil
- hash[num] = longest_consec
- break
- else
- longest_consec += hash[num + longest_consec]
- hash[num] = longest_consec
- break
- end
+ set = Set.new(nums)
+ set.reduce(0) do |longest, num|
+ if !set.include?(num-1)
+ length = 0
+ while set.include?(num + length) do
+ length += 1
+ end
+ next(longest > length ? longest : length)
+ end
+
+ longest
  end
- end
-
- hash.max_by { |_k, v| v }[1]
 end