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author | Vincent Ambo <mail@tazj.in> | 2021-12-13T22·51+0300 |
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committer | Vincent Ambo <mail@tazj.in> | 2021-12-13T23·15+0300 |
commit | 019f8fd2113df4c5247c3969c60fd4f0e08f91f7 (patch) | |
tree | 76a857f61aa88f62a30e854651e8439db77fd0ea /users/wpcarro/scratch/facebook/graph-coloring.py | |
parent | 464bbcb15c09813172c79820bcf526bb10cf4208 (diff) | |
parent | 6123e976928ca3d8d93f0b2006b10b5f659eb74d (diff) |
subtree(users/wpcarro): docking briefcase at '24f5a642' r/3226
git-subtree-dir: users/wpcarro git-subtree-mainline: 464bbcb15c09813172c79820bcf526bb10cf4208 git-subtree-split: 24f5a642af3aa1627bbff977f0a101907a02c69f Change-Id: I6105b3762b79126b3488359c95978cadb3efa789
Diffstat (limited to 'users/wpcarro/scratch/facebook/graph-coloring.py')
-rw-r--r-- | users/wpcarro/scratch/facebook/graph-coloring.py | 60 |
1 files changed, 60 insertions, 0 deletions
diff --git a/users/wpcarro/scratch/facebook/graph-coloring.py b/users/wpcarro/scratch/facebook/graph-coloring.py new file mode 100644 index 000000000000..e5b6d9c89332 --- /dev/null +++ b/users/wpcarro/scratch/facebook/graph-coloring.py @@ -0,0 +1,60 @@ +from collections import deque + +class Palette(object): + def __init__(self, n): + self.i = 0 + self.colors = list(range(n)) + + def get(self): + return self.colors[self.i] + + def advance(self): + self.i += 1 % len(self.colors) + +class GraphNode(object): + def __init__(self, label): + self.label = label + self.neighbors = set() + self.color = None + + def __repr__(self): + result = [] + xs = deque() + xs.append(self) + seen = set() + while xs: + node = xs.popleft() + result.append('{} ({})'.format(node.label, str(node.color))) + for c in node.neighbors: + if c.label not in seen: + xs.append(c) + seen.add(node.label) + return ', '.join(result) + +def color_graph(graph, d): + seen = set() + start = graph + xs = deque() + palette = Palette(d + 1) + xs.append((start, palette.get())) + while xs: + x, color = xs.popleft() + x.color = color + for c in x.neighbors: + if c.label not in seen: + palette.advance() + xs.append((c, palette.get())) + seen.add(x.label) + +a = GraphNode('a') +b = GraphNode('b') +c = GraphNode('c') + +a.neighbors.add(b) +b.neighbors.add(a) +b.neighbors.add(c) +c.neighbors.add(b) + +print(a) +color_graph(a, 3) +print(a) |