Nataliia Getlin - Rock - C15

graphs/possible_bipartition.py

@@ -1,12 +1,33 @@
 # Can be used for BFS
-from collections import deque 
+from collections import deque
+import collections 
 
 def possible_bipartition(dislikes):
     """ Will return True or False if the given graph
         can be bipartitioned without neighboring nodes put
         into the same partition.
-        Time Complexity: ?
-        Space Complexity: ?
+        Time Complexity: O(N+E)
+        Space Complexity: O(N)
+        where N - number of vertices/nodes, E - number of edges
     """
-    pass
+    if not dislikes:
+        return True
+
+    belongs_to_group = [False for i in range(len(dislikes))]
+    queue = collections.deque()
+
+    queue.append(1)
+    belongs_to_group[1] = "group_a"
+
+    while queue:
+        current_dog = queue.popleft()
+        for unwanted_dog in dislikes[current_dog]:
+            if belongs_to_group[unwanted_dog] == belongs_to_group[current_dog]:
+                return False
+            elif belongs_to_group[unwanted_dog] == False:
+                belongs_to_group[unwanted_dog] = "group_b" if belongs_to_group[current_dog] == "group_a" else "group_a"
+                queue.append(unwanted_dog)
+
+    return True
+
 

tests/test_possible_bipartition.py

@@ -1,78 +1,103 @@
 from graphs.possible_bipartition import possible_bipartition
 
 
+def test_my_example():
+    # Arrange
+    dislikes = [[],
+                [2],  # 1
+                [1],  # 2
+                [4],  # 3
+                [3],  # 4
+                [6],  # 5
+                [5, 7],  # 6
+                [6, 8],  # 7
+                [7, 9],  # 8
+                [8]  # 9
+                ]
+
+    # Act
+    answer = possible_bipartition(dislikes)
+
+    # Assert
+    assert answer
+
+
 def test_example_1():
     # Arrange
-    dislikes = [ [],
-      [2, 3],
-      [1, 4],
-      [1],
-      [2]
-    ]
+    dislikes = [[],
+                [2, 3],
+                [1, 4],
+                [1],
+                [2]
+                ]
 
     # Act
     answer = possible_bipartition(dislikes)
 
     # Assert
     assert answer
 
+
 def test_example_2():
     # Arrange
-    dislikes =  [ [],
-      [2, 3],
-      [1, 3],
-      [1, 2]
-    ]
+    dislikes = [[],
+                [2, 3],
+                [1, 3],
+                [1, 2]
+                ]
 
     # Act
     answer = possible_bipartition(dislikes)
 
     # Assert
     assert not answer
 
+
 def test_example_r():
     # Arrange
-    dislikes = [ [],
-      [2, 5],
-      [1, 3],
-      [2, 4],
-      [3, 5],
-      [1, 4]
-    ]
+    dislikes = [[],
+                [2, 5],
+                [1, 3],
+                [2, 4],
+                [3, 5],
+                [1, 4]
+                ]
 
     # Act
     answer = possible_bipartition(dislikes)
 
     # Assert
     assert not answer
 
+
 def test_will_return_true_for_a_graph_which_can_be_bipartitioned():
     # Arrange
-    dislikes = [ [3, 6],
-      [2, 5],
-      [1, 3],
-      [0, 2],
-      [5],
-      [1, 4],
-      [0]
-    ]
+    dislikes = [[3, 6],
+                [2, 5],
+                [1, 3],
+                [0, 2],
+                [5],
+                [1, 4],
+                [0]
+                ]
 
     # Act
     answer = possible_bipartition(dislikes)
 
     # Assert
     assert answer
 
+
 def test_will_return_false_for_graph_which_cannot_be_bipartitioned():
     # Arrange
-    dislikes = [ [3, 6],
-      [2, 5],
-      [1, 3],
-      [0, 2, 4],
-      [3, 5],
-      [1, 4],
-      [0]
-    ]
+    dislikes = [[3, 6],
+                [2, 5],
+                [1, 3],
+                [0, 2, 4],
+                [3, 5],
+                [1, 4],
+                [0]
+                ]
 
     # Act
     answer = possible_bipartition(dislikes)
@@ -83,19 +108,20 @@ def test_will_return_false_for_graph_which_cannot_be_bipartitioned():
 
 def test_will_return_true_for_empty_graph():
     assert possible_bipartition([])
-
+
+
 def test_will_return_false_for_another_graph_which_cannot_be_bipartitioned():
     # Arrange
-    dislikes = [ [3, 6],
-      [2, 5],
-      [1, 3],
-      [0, 2, 4],
-      [3, 5],
-      [1, 4],
-      [0],
-      [8],
-      [7]
-    ]
+    dislikes = [[3, 6],
+                [2, 5],
+                [1, 3],
+                [0, 2, 4],
+                [3, 5],
+                [1, 4],
+                [0],
+                [8],
+                [7]
+                ]
 
     # Act
     answer = possible_bipartition(dislikes)