Created
January 21, 2014 14:19
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greedy set cover implementation (lurk more here http://en.wikipedia.org/wiki/Set_cover_problem) targetSet - the set you want to cover
subSets - dictionary of subsets to cover the target set (uncomment the "#result" in case you want to see the resulting set also)
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| def greedySetCover(targetSet, subSets): | |
| if not subSets: | |
| return None | |
| probeKey = max(subSets, key=lambda x: len(targetSet.intersection(subSets[x]))) | |
| probeSet = subSets[probeKey] | |
| #result = set() | |
| resKeys = set() | |
| while len(targetSet) > 0: | |
| #result.update(probeSet) | |
| targetSet = targetSet.difference(probeSet) | |
| resKeys.add(probeKey) | |
| del(subSets[probeKey]) | |
| if subSets: | |
| probeKey = max(subSets, key=lambda x: len(targetSet.intersection(subSets[x]))) | |
| probeSet = subSets[probeKey] | |
| if len(targetSet.intersection(probeSet)) == 0: | |
| break | |
| else: | |
| break | |
| #return result, resKeys | |
| return resKeys |
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