From 84b0a2ed0951f567b52d24e14a4b8377e90638c4 Mon Sep 17 00:00:00 2001
From: beauttie <15842537+beauttie@users.noreply.github.com>
Date: Thu, 20 May 2021 00:31:26 -0700
Subject: [PATCH 1/2] Draft of possible_bipartition

---
 lib/possible_bipartition.rb | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/lib/possible_bipartition.rb b/lib/possible_bipartition.rb
index 69507f1..cb43706 100644
--- a/lib/possible_bipartition.rb
+++ b/lib/possible_bipartition.rb
@@ -1,4 +1,23 @@
 
 def possible_bipartition(dislikes)
-  raise NotImplementedError, "possible_bipartition isn't implemented yet"
+  return true if dislikes.empty? 
+
+  group_num = Array.new(dislikes.length)
+  group_num[0] = 1
+  queue = Queue.new
+  queue.enq(0)
+  while !queue.empty?
+    current = queue.deq
+    dislikes[current].each do |dog|
+      if group_num[dog].nil?
+        group_num[dog] = group_num[current] == 1 ? 2 : 1
+        queue.enq(dog)
+      elsif group_num[dog] == group_num[current]
+        return false
+      end
+    end
+    queue.enq(current + 1) unless current == dislikes.length - 1
+  end
+
+  return true
 end

From 051a691637bb9d8ac5acacacc8b8cc3d37320f7f Mon Sep 17 00:00:00 2001
From: beauttie <15842537+beauttie@users.noreply.github.com>
Date: Thu, 20 May 2021 00:42:24 -0700
Subject: [PATCH 2/2] Implement possible_bipartition to pass all tests

---
 lib/possible_bipartition.rb | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/lib/possible_bipartition.rb b/lib/possible_bipartition.rb
index cb43706..e3aa0b5 100644
--- a/lib/possible_bipartition.rb
+++ b/lib/possible_bipartition.rb
@@ -3,6 +3,7 @@ def possible_bipartition(dislikes)
   return true if dislikes.empty? 
 
   group_num = Array.new(dislikes.length)
+  # Element at index i indicates group number for dog i
   group_num[0] = 1
   queue = Queue.new
   queue.enq(0)
@@ -10,13 +11,15 @@ def possible_bipartition(dislikes)
     current = queue.deq
     dislikes[current].each do |dog|
       if group_num[dog].nil?
+        # Assign dogs disliked by the current dog to the other group
         group_num[dog] = group_num[current] == 1 ? 2 : 1
         queue.enq(dog)
+      # If a dog disliked by the current dog is in the same group
       elsif group_num[dog] == group_num[current]
         return false
       end
     end
-    queue.enq(current + 1) unless current == dislikes.length - 1
+    queue.enq(current + 1) if dislikes[current].empty?
   end
 
   return true