# find all paths from start to goal in graph
def search(start, goal, graph):
solns = []
generate([start], goal, solns, graph) # collect paths
solns.sort(lambda x, y: cmp(len(x), len(y))) # sort by path length
return solns
def generate(path, goal, solns, graph):
state = path[-1]
if state == goal: # found goal here
solns.append(path) # change solns in-place
else: # check all arcs here
for arc in graph[state]: # skip cycles on path
if arc not in path:
generate(path + [arc], goal, solns, graph)
if __name__ == '__main__':
import gtestfunc
gtestfunc.tests(search)
"graph search, using paths stack instead of recursion"
def search(start, goal, graph):
solns = generate(([start], []), goal, graph)
solns.sort(key=lambda x: len(x))
return solns
def generate(paths, goal, graph): # returns solns list
solns = [] # use a tuple-stack
while paths:
front, paths = paths # pop the top path
state = front[-1]
if state == goal:
solns.append(front) # goal on this path
else:
for arc in graph[state]: # add all extensions
if arc not in front:
paths = (front + [arc]), paths
return solns
if __name__ == '__main__':
import gtestfunc
gtestfunc.tests(search)
