30 lines
827 B
Plaintext
30 lines
827 B
Plaintext
use std::collections::BTreeSet;
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fn powerset<T: Ord + Clone>(mut set: BTreeSet<T>) -> BTreeSet<BTreeSet<T>> {
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if set.is_empty() {
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let mut powerset = BTreeSet::new();
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powerset.insert(set);
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return powerset;
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}
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// Access the first value. This could be replaced with `set.pop_first().unwrap()`
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// But this is an unstable feature
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let entry = set.iter().nth(0).unwrap().clone();
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set.remove(&entry);
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let mut powerset = powerset(set);
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for mut set in powerset.clone().into_iter() {
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set.insert(entry.clone());
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powerset.insert(set);
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}
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powerset
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}
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fn main() {
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let set = (1..5).collect();
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let set = powerset(set);
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println!("{:?}", set);
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let set = ["a", "b", "c", "d"].iter().collect();
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let set = powerset(set);
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println!("{:?}", set);
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}
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