Skip to content

Add doctests to DFS and BFS. Contributes to #9943 #11757

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 2 commits into
base: master
Choose a base branch
from
Open

Add doctests to DFS and BFS. Contributes to #9943 #11757

Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
3cd9201
Correct implementation and add tests for dfs and bfs
prak74 Oct 4, 2024
c84aca2
Ruff check
prak74 Oct 4, 2024
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
256 changes: 193 additions & 63 deletions graphs/directed_and_undirected_weighted_graph.py
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,18 @@ def __init__(self):
# adding the weight is optional
# handles repetition
def add_pair(self, u, v, w=1):
"""
Adds a directed edge u->v with weight w.
>>> dg = DirectedGraph()
>>> dg.add_pair(-1,2)
>>> dg.add_pair(1,3,5)
>>> dg.add_pair(1,3,5)
>>> dg.add_pair(1,3,6)
>>> dg.all_nodes()
[-1, 2, 1, 3]
>>> dg.graph[1]
[[5, 3], [6, 3]]
"""
if self.graph.get(u):
if self.graph[u].count([w, v]) == 0:
self.graph[u].append([w, v])
Expand All @@ -23,53 +35,94 @@ def add_pair(self, u, v, w=1):
self.graph[v] = []

def all_nodes(self):
"""
Returns list of all nodes in the graph.
>>> dg = DirectedGraph()
>>> dg.all_nodes()
[]
>>> dg.add_pair(1,1)
>>> dg.all_nodes()
[1]
>>> dg.add_pair(2,3,3)
>>> dg.all_nodes()
[1, 2, 3]
"""
return list(self.graph)

# handles if the input does not exist
def remove_pair(self, u, v):
"""
Removes all edges u->v if it exists.
>>> dg = DirectedGraph()
>>> dg.remove_pair(1,2) # silently exits
>>> dg.add_pair(0,5,2)
>>> dg.graph[0]
[[2, 5]]
>>> dg.remove_pair(5,0)
>>> dg.graph[0]
[[2, 5]]
>>> dg.remove_pair(0,5)
>>> dg.graph[0]
[]
"""
if self.graph.get(u):
for _ in self.graph[u]:
if _[1] == v:
self.graph[u].remove(_)

# if no destination is meant the default value is -1
def dfs(self, s=-2, d=-1):
if s == d:
return []
"""
Performs depth first search from s to find d.
Returns the path s->d as a list.
Returns dfs from s if d is not found
>>> dg = DirectedGraph()
>>> dg.dfs()
[]
>>> dg.add_pair(1,1)
>>> dg.dfs(1,1)
[1]
>>> dg = DirectedGraph()
>>> dg.add_pair(0,1)
>>> dg.add_pair(0,2)
>>> dg.add_pair(1,3)
>>> dg.add_pair(1,4)
>>> dg.add_pair(1,5)
>>> dg.add_pair(2,5)
>>> dg.add_pair(5,6)
>>> dg.dfs(0,6)
[0, 2, 5, 6]
>>> dg.dfs(1,6)
[1, 5, 6]
>>> dg.dfs()
[0, 2, 5, 6, 1, 4, 3]
>>> dg.dfs(1,0)
[1, 5, 6, 4, 3]
"""
stack = []
visited = []
if s == -2:
s = next(iter(self.graph))
stack.append(s)
visited.append(s)
ss = s

while True:
# check if there is any non isolated nodes
if len(self.graph[s]) != 0:
ss = s
for node in self.graph[s]:
if visited.count(node[1]) < 1:
if node[1] == d:
visited.append(d)
return visited
else:
stack.append(node[1])
visited.append(node[1])
ss = node[1]
break

# check if all the children are visited
if s == ss:
stack.pop()
if len(stack) != 0:
s = stack[len(stack) - 1]
if self.graph.get(s, None):
pass # -2 is a node
elif len(self.graph) > 0:
s = next(iter(self.graph))
else:
s = ss
return [] # Graph empty
stack.append(s)

# check if se have reached the starting point
if len(stack) == 0:
return visited
# Run dfs
while len(stack) > 0:
s = stack.pop()
visited.append(s)
# If reached d, return
if s == d:
break

# add not visited child nodes to stack
for _, ss in self.graph[s]:
if visited.count(ss) < 1:
stack.append(ss)
return visited

# c is the count of nodes you want and if you leave it or pass -1 to the function
# the count will be random from 10 to 10000
Expand All @@ -84,12 +137,42 @@ def fill_graph_randomly(self, c=-1):
self.add_pair(i, n, 1)

def bfs(self, s=-2):
"""
Performs breadth first search from s
Returns list.
>>> dg = DirectedGraph()
>>> dg.bfs()
[]
>>> dg.add_pair(1,1)
>>> dg.bfs(1)
[1]
>>> dg = DirectedGraph()
>>> dg.add_pair(0,1)
>>> dg.add_pair(0,2)
>>> dg.add_pair(1,3)
>>> dg.add_pair(1,4)
>>> dg.add_pair(1,5)
>>> dg.add_pair(2,5)
>>> dg.add_pair(5,6)
>>> dg.bfs(0)
[0, 1, 2, 3, 4, 5, 6]
>>> dg.bfs(1)
[1, 3, 4, 5, 6]
>>> dg.bfs()
[0, 1, 2, 3, 4, 5, 6]
"""
d = deque()
visited = []
if s == -2:
s = next(iter(self.graph))
if self.graph.get(s, None):
pass # -2 is a node
elif len(self.graph) > 0:
s = next(iter(self.graph))
else:
return [] # Graph empty
d.append(s)
visited.append(s)
# Run bfs
while d:
s = d.popleft()
if len(self.graph[s]) != 0:
Expand Down Expand Up @@ -300,42 +383,60 @@ def remove_pair(self, u, v):

# if no destination is meant the default value is -1
def dfs(self, s=-2, d=-1):
if s == d:
return []
"""
Performs depth first search from s to find d.
Returns the path s->d as a list.
Returns dfs from s if d is not found
>>> ug = Graph()
>>> ug.dfs()
[]
>>> ug.add_pair(1,1)
>>> ug.dfs(1,1)
[1]
>>> ug = Graph()
>>> ug.add_pair(0,1)
>>> ug.add_pair(0,2)
>>> ug.add_pair(1,3)
>>> ug.add_pair(1,4)
>>> ug.add_pair(1,5)
>>> ug.add_pair(2,5)
>>> ug.add_pair(5,6)
>>> ug.dfs(0,6)
[0, 2, 5, 6]
>>> ug.dfs(1,6)
[1, 5, 6]
>>> ug.dfs()
[0, 2, 5, 6, 1, 4, 3]
>>> ug.dfs(1,0)
[1, 5, 6, 2, 0]
"""
stack = []
visited = []
if s == -2:
s = next(iter(self.graph))
if self.graph.get(s, None):
pass # -2 is a node
elif len(self.graph) > 0:
s = next(iter(self.graph))
else:
return [] # Graph empty
stack.append(s)
visited.append(s)
ss = s

while True:
# check if there is any non isolated nodes
if len(self.graph[s]) != 0:
ss = s
for node in self.graph[s]:
if visited.count(node[1]) < 1:
if node[1] == d:
visited.append(d)
return visited
else:
stack.append(node[1])
visited.append(node[1])
ss = node[1]
break

# check if all the children are visited
if s == ss:
stack.pop()
if len(stack) != 0:
s = stack[len(stack) - 1]
# Run dfs
while len(stack) > 0:
s = stack.pop()
if visited.count(s) == 1:
continue
else:
s = ss

# check if se have reached the starting point
if len(stack) == 0:
return visited
visited.append(s)
# If reached d, return
if s == d:
break

# add not visited child nodes to stack
for _, ss in self.graph[s]:
if visited.count(ss) < 1:
stack.append(ss)
return visited

# c is the count of nodes you want and if you leave it or pass -1 to the function
# the count will be random from 10 to 10000
Expand All @@ -350,10 +451,39 @@ def fill_graph_randomly(self, c=-1):
self.add_pair(i, n, 1)

def bfs(self, s=-2):
"""
Performs breadth first search from s
Returns list.
>>> ug = Graph()
>>> ug.bfs()
[]
>>> ug.add_pair(1,1)
>>> ug.bfs(1)
[1]
>>> ug = Graph()
>>> ug.add_pair(0,1)
>>> ug.add_pair(0,2)
>>> ug.add_pair(1,3)
>>> ug.add_pair(1,4)
>>> ug.add_pair(1,5)
>>> ug.add_pair(2,5)
>>> ug.add_pair(5,6)
>>> ug.bfs(0)
[0, 1, 2, 3, 4, 5, 6]
>>> ug.bfs(1)
[1, 0, 3, 4, 5, 2, 6]
>>> ug.bfs()
[0, 1, 2, 3, 4, 5, 6]
"""
d = deque()
visited = []
if s == -2:
s = next(iter(self.graph))
if self.graph.get(s, None):
pass # -2 is a node
elif len(self.graph) > 0:
s = next(iter(self.graph))
else:
return [] # Graph empty
d.append(s)
visited.append(s)
while d:
Expand Down