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https://github.com/donnemartin/interactive-coding-challenges.git
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71 lines
2.1 KiB
Python
71 lines
2.1 KiB
Python
from enum import Enum # Python 2 users: Run pip install enum34
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class State(Enum):
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unvisited = 0
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visiting = 1
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visited = 2
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class Node:
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def __init__(self, key):
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self.key = key
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self.visit_state = State.unvisited
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self.incoming_edges = 0
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self.adj_nodes = {} # Key = key, val = Node
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self.adj_weights = {} # Key = key, val = weight
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def __repr__(self):
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return str(self.key)
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def __lt__(self, other):
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return self.key < other.key
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def add_neighbor(self, neighbor, weight=0):
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if neighbor is None:
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raise Exception('Invalid neighbor')
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neighbor.incoming_edges += 1
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self.adj_weights[neighbor.key] = weight
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self.adj_nodes[neighbor.key] = neighbor
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def remove_neighbor(self, neighbor):
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if neighbor is None:
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raise Exception('Invalid neighbor')
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if neighbor.key in self.adj_nodes:
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neighbor.incoming_edges -= 1
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del self.adj_weights[neighbor.key]
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del self.adj_nodes[neighbor.key]
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else:
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raise Exception('Invalid neighbor')
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class Graph:
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def __init__(self):
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self.nodes = {} # Key = key, val = Node
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def add_node(self, key):
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if key is None:
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raise Exception('Invalid key')
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if key in self.nodes:
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return self.nodes[key]
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self.nodes[key] = Node(key)
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return self.nodes[key]
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def add_edge(self, source_key, dest_key, weight=0):
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if source_key is None or dest_key is None:
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raise Exception('Invalid key')
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if source_key not in self.nodes:
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self.add_node(source_key)
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if dest_key not in self.nodes:
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self.add_node(dest_key)
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self.nodes[source_key].add_neighbor(self.nodes[dest_key],
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weight)
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def add_undirected_edge(self, source_key, dest_key, weight=0):
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if source_key is None or dest_key is None:
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raise Exception('Invalid key')
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self.add_edge(source_key, dest_key, weight)
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self.nodes[dest_key].add_neighbor(self.nodes[source_key],
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weight) |