15

Author: TedTran2019

ruby/15-3Sum.rb

@@ -0,0 +1,23 @@
+def three_sum(nums)
+  sums = []
+  nums.sort! # This is to get rid of duplicate solutions
+  nums.each_with_index do |num, idx|
+    next if idx.positive? && num == nums[idx - 1]
+
+    left = idx + 1
+    right = nums.length - 1
+    while left < right
+      case num + nums[left] + nums[right] <=> 0
+      when 1
+        right -= 1
+      when 0
+        sums << [num, nums[left], nums[right]]
+        left += 1
+        left += 1 while nums[left] == nums[left - 1] && left < right
+      when -1
+        left += 1
+      end
+    end
+  end
+  sums
+end