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[pre-commit.ci] auto fixes from pre-commit.com hooks

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pre-commit-ci[bot] 2024-10-11 00:15:55 +00:00
parent d4a8dcc245
commit ca0845e60a
1 changed files with 20 additions and 13 deletions
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33
graphs/bellman_ford.py
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@ -17,16 +17,18 @@ def print_distance_and_paths(distance: list[float], paths: list[list[int]], src:
print(f"{vertex}\t\t{dist}\t\t\t\t{path_str}")
def check_negative_cycle(graph: list[Edge], distance: list[float],
predecessor: list[int]) -> bool:
def check_negative_cycle(
graph: list[Edge], distance: list[float], predecessor: list[int]
) -> bool:
"""
Checks if there is a negative weight cycle reachable from the source vertex.
If found, return True, indicating a negative cycle.
"""
for edge in graph:
if (distance[edge.src] != float("inf") and
distance[edge.src] + edge.weight
< distance[edge.dst]):
if (
distance[edge.src] != float("inf")
and distance[edge.src] + edge.weight < distance[edge.dst]
):
# Update predecessors to indicate a cycle for affected paths
# Use -1 as a marker for negative cycle detection
predecessor[edge.dst] = -1
@ -34,8 +36,9 @@ predecessor: list[int]) -> bool:
return False
def reconstruct_paths(predecessor: list[int],
vertex_count: int, src: int) -> list[list[int]]:
def reconstruct_paths(
predecessor: list[int], vertex_count: int, src: int
) -> list[list[int]]:
"""
Reconstructs the shortest paths from the source vertex to
each vertex using the predecessor list.
@ -56,8 +59,9 @@ vertex_count: int, src: int) -> list[list[int]]:
return paths
def bellman_ford(graph: list[Edge],
vertex_count: int, src: int) -> tuple[list[float], list[list[int]]]:
def bellman_ford(
graph: list[Edge], vertex_count: int, src: int
) -> tuple[list[float], list[list[int]]]:
"""
Returns the shortest paths from a vertex src to all other vertices,
including path reconstruction.
@ -69,8 +73,10 @@ vertex_count: int, src: int) -> tuple[list[float], list[list[int]]]:
# Step 1: Relax edges repeatedly
for _ in range(vertex_count - 1):
for edge in graph:
if (distance[edge.src] != float("inf") and
distance[edge.src] + edge.weight < distance[edge.dst]):
if (
distance[edge.src] != float("inf")
and distance[edge.src] + edge.weight < distance[edge.dst]
):
distance[edge.dst] = distance[edge.src] + edge.weight
predecessor[edge.dst] = edge.src
@ -97,8 +103,9 @@ if __name__ == "__main__":
for i in range(E):
print(f"Edge {i + 1}")
src, dest, weight = map(int,
input("Enter source, destination, weight: ").strip().split())
src, dest, weight = map(
int, input("Enter source, destination, weight: ").strip().split()
)
if src < 0 or src >= V or dest < 0 or dest >= V:
print(f"Invalid vertices: src and dest should be between 0 and {V - 1}")
continue