feat(ancestors): add python solution

Author: jordanpaulchan

ancestors/ancestors.py

@@ -0,0 +1,111 @@
+def create_ancestor_graph(relationships):
+ ancestor_graph = {}
+ for parent, child in relationships:
+ if parent not in ancestor_graph:
+ ancestor_graph[parent] = []
+
+ if child not in ancestor_graph:
+ ancestor_graph[child] = []
+
+ ancestor_graph[child].append(parent)
+
+ return ancestor_graph
+
+
+def earliest_ancestor(child, ancestor_graph):
+ if child not in ancestor_graph or not ancestor_graph[child]:
+ return -1
+
+ queue = [child]
+ visited = set()
+
+ while queue:
+ tempq = []
+ for person in queue:
+ for ancestor in ancestor_graph[person]:
+ if ancestor not in visited:
+ visited.add(ancestor)
+ tempq.append(ancestor)
+
+ if not tempq:
+ return queue[0]
+
+ queue = tempq
+
+ return -1
+
+
+def get_all_ancestors(child, ancestor_graph):
+ if child not in ancestor_graph or not ancestor_graph[child]:
+ return set()
+
+ queue = [child]
+ visited = set()
+
+ while queue:
+ tempq = []
+ for person in queue:
+ for ancestor in ancestor_graph[person]:
+ if ancestor not in visited:
+ visited.add(ancestor)
+ tempq.append(ancestor)
+
+ queue = tempq
+
+ return visited
+
+
+def has_common_ancestor(child1, child2, ancestor_graph):
+ child1_ancestors = get_all_ancestors(child1, ancestor_graph)
+ child2_ancestors = get_all_ancestors(child2, ancestor_graph)
+
+ return len(child1_ancestors & child2_ancestors) > 0
+
+
+def one_or_zero_parents(ancestor_graph):
+ children = []
+ for child in ancestor_graph.keys():
+ if len(ancestor_graph[child]) <= 1:
+ children.append(child)
+ return children
+
+
+parent_child_pairs1 = [
+ (2, 3), (3, 15), (3, 6), (5, 6), (5, 7),
+ (4, 5), (4, 8), (4, 9), (9, 11), (14, 4),
+]
+ancestor_graph1 = create_ancestor_graph(parent_child_pairs1)
+print(earliest_ancestor(8, ancestor_graph1)) # 14
+print(earliest_ancestor(7, ancestor_graph1)) # 14
+print(earliest_ancestor(6, ancestor_graph1)) # 14
+print(earliest_ancestor(15, ancestor_graph1)) # 2
+print(earliest_ancestor(14, ancestor_graph1)) # -1
+print()
+print(has_common_ancestor(3, 8, ancestor_graph1)) # false
+print(has_common_ancestor(5, 8, ancestor_graph1)) # true
+print(has_common_ancestor(6, 8, ancestor_graph1)) # true
+print(has_common_ancestor(6, 9, ancestor_graph1)) # true
+print(has_common_ancestor(1, 3, ancestor_graph1)) # false
+print(has_common_ancestor(7, 11, ancestor_graph1)) # true
+print(has_common_ancestor(6, 5, ancestor_graph1)) # true
+print(has_common_ancestor(5, 6, ancestor_graph1)) # true
+print()
+print(one_or_zero_parents(ancestor_graph1))
+print()
+
+parent_child_pairs2 = [
+ (2, 3), (3, 15), (3, 6), (5, 6), (5, 7),
+ (4, 5), (4, 8), (4, 9), (9, 11), (14, 2),
+]
+ancestor_graph2 = create_ancestor_graph(parent_child_pairs2)
+print(earliest_ancestor(8, ancestor_graph2)) # 4
+print(earliest_ancestor(7, ancestor_graph2)) # 4
+print(earliest_ancestor(6, ancestor_graph2)) # 14
+print(earliest_ancestor(15, ancestor_graph2)) # 14
+print(earliest_ancestor(14, ancestor_graph2)) # -1
+print()
+print(has_common_ancestor(4, 12, ancestor_graph2)) # false
+print(has_common_ancestor(11, 6, ancestor_graph2)) # true
+print(has_common_ancestor(11, 3, ancestor_graph2)) # false
+print()
+print(one_or_zero_parents(ancestor_graph2))