Dianna T.

lib/possible_bipartition.rb

@@ -1,4 +1,67 @@
+# Depth First Search
+# Time: O(n + e) where n is the number of nodes in the graph and e is the number of edges.
+# Space: O(n) where n is the number of nodes in the graph.
+def possible_bipartition(dislikes)
+  total_puppies = dislikes.length
+  groups = {}
+  stack = []
+
+  total_puppies.times do |i|
+    if !groups[i]
+      stack.push(i)
+      groups[i] = 1
+    end
+
+    while !stack.empty?
+      current = stack.pop 
+      neighbors = dislikes[current]
+
+      neighbors.each do |puppy|
+        if !groups[puppy]
+          stack.push(puppy)
+          groups[puppy] = groups[current] * (-1)
+        else
+          if groups[puppy] == groups[current]
+            return false
+          end
+        end
+      end
+    end
+  end
+
+  return true
+end
 
+# Breadth First Search
+# Time: O(n + e) where n is the number of nodes in the graph and e is the number of edges.
+# Space: O(n) where n is the number of nodes in the graph.
 def possible_bipartition(dislikes)
-  raise NotImplementedError, "possible_bipartition isn't implemented yet"
+  total_puppies = dislikes.length
+  groups = {}
+  queue = []
+
+  total_puppies.times do |i|
+    if !groups[i]
+      queue.push(i)
+      groups[i] = 1
+    end
+
+    while !queue.empty?
+      current = queue.shift 
+      neighbors = dislikes[current]
+
+      neighbors.each do |puppy|
+        if !groups[puppy]
+          queue.push(puppy)
+          groups[puppy] = groups[current] * (-1)
+        else
+          if groups[puppy] == groups[current]
+            return false
+          end
+        end
+      end
+    end
+  end
+
+  return true
 end