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Original file line number | Diff line number | Diff line change |
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use std::collections::HashMap; | ||
use std::default::Default; | ||
use std::hash::Hash; | ||
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#[derive(PartialEq, Eq, Debug, Default, Clone)] | ||
pub(crate) struct MultiSet<T: Hash + Eq> { | ||
pub(crate) map: HashMap<T, usize>, | ||
cardinality: usize, | ||
} | ||
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impl<T: Hash + Eq> MultiSet<T> { | ||
pub(crate) fn new() -> Self { | ||
Self { | ||
map: Default::default(), | ||
cardinality: 0, | ||
} | ||
} | ||
pub(crate) fn add(&mut self, element: T) { | ||
self.add_n(element, 1); | ||
} | ||
pub(crate) fn add_n(&mut self, element: T, n: usize) { | ||
*self.map.entry(element).or_insert(0) += n; | ||
self.cardinality += n; | ||
} | ||
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pub(crate) fn get(&self, element: &T) -> Option<usize> { | ||
self.map.get(element).copied() | ||
} | ||
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#[allow(dead_code)] | ||
pub(crate) fn cardinality(&self) -> usize { | ||
self.cardinality | ||
} | ||
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#[allow(dead_code)] | ||
pub(crate) fn len(&self) -> usize { | ||
self.map.len() | ||
} | ||
} | ||
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#[cfg(test)] | ||
mod test { | ||
use super::*; | ||
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#[test] | ||
fn test_multiset() { | ||
let mut m = MultiSet::<usize>::new(); | ||
let mut c = 0; | ||
let n = 5; | ||
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for i in 1..n { | ||
for _ in 0..i { | ||
m.add(i); | ||
} | ||
c += i; | ||
assert_eq!(i, m.len()); | ||
assert_eq!(c, m.cardinality()); | ||
assert_eq!(Some(i), m.get(&i)); | ||
assert_eq!(None, m.get(&(i + n))); | ||
} | ||
} | ||
} |
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