Merge branch 'nick-jiang-master'

Author: faif

graph_search.py

@@ -10,10 +10,10 @@ class GraphSearch:
  def __init__(self, graph):
  self.graph = graph
 
- def find_path(self, start, end, path=[]):
+ def find_path(self, start, end, path=None):
  self.start = start
  self.end = end
- self.path = path
+ self.path = path if path else []
 
  self.path += [self.start]
  if self.start == self.end:
@@ -27,37 +27,37 @@ def find_path(self, start, end, path=[]):
  return newpath
  return None
 
- def find_all_path(self, start, end, path=[]):
+ def find_all_path(self, start, end, path=None):
  self.start = start
  self.end = end
- self.path = path
- self.path += [self.start]
+ _path = path if path else []
+ _path += [self.start]
  if self.start == self.end:
- return [self.path]
+ return [_path]
  if self.start not in self.graph:
  return []
  paths = []
  for node in self.graph[self.start]:
- if node not in self.path:
- newpaths = self.find_all_path(node, self.end, self.path)
+ if node not in _path:
+ newpaths = self.find_all_path(node, self.end, _path[:])
  for newpath in newpaths:
  paths.append(newpath)
  return paths
 
- def find_shortest_path(self, start, end, path=[]):
+ def find_shortest_path(self, start, end, path=None):
  self.start = start
  self.end = end
- self.path = path
+ _path = path if path else []
 
- self.path += [self.start]
+ _path += [self.start]
  if self.start == self.end:
- return self.path
+ return _path
  if self.start not in self.graph:
  return None
  shortest = None
  for node in self.graph[self.start]:
- if node not in self.path:
- newpath = self.find_shortest_path(node, self.end, self.path)
+ if node not in _path:
+ newpath = self.find_shortest_path(node, self.end, _path[:])
  if newpath:
  if not shortest or len(newpath) < len(shortest):
  shortest = newpath
@@ -82,5 +82,5 @@ def find_shortest_path(self, start, end, path=[]):
 
 ### OUTPUT ###
 # ['A', 'B', 'C', 'D']
-# [['A', 'B', 'C', 'D']]
-# ['A', 'B', 'C', 'D']
+# [['A', 'B', 'C', 'D'], ['A', 'B', 'D'], ['A', 'C', 'D']]
+# ['A', 'B', 'D']