61 lines
1.3 KiB
Python
61 lines
1.3 KiB
Python
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from collections import deque
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class Palette(object):
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def __init__(self, n):
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self.i = 0
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self.colors = list(range(n))
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def get(self):
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return self.colors[self.i]
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def advance(self):
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self.i += 1 % len(self.colors)
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class GraphNode(object):
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def __init__(self, label):
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self.label = label
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self.neighbors = set()
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self.color = None
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def __repr__(self):
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result = []
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xs = deque()
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xs.append(self)
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seen = set()
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while xs:
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node = xs.popleft()
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result.append('{} ({})'.format(node.label, str(node.color)))
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seen.add(node.label)
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for c in node.neighbors:
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if c.label not in seen:
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xs.append(c)
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return ', '.join(result)
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def color_graph(graph, d):
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seen = set()
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start = graph
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xs = deque()
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palette = Palette(d + 1)
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xs.append((start, palette.get()))
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while xs:
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x, color = xs.popleft()
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x.color = color
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seen.add(x.label)
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for c in x.neighbors:
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if c.label not in seen:
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palette.advance()
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xs.append((c, palette.get()))
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a = GraphNode('a')
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b = GraphNode('b')
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c = GraphNode('c')
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a.neighbors.add(b)
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b.neighbors.add(a)
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b.neighbors.add(c)
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c.neighbors.add(b)
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print(a)
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color_graph(a, 3)
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print(a)
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