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This commit is contained in:
wborgeaud 2021-07-02 14:42:40 +02:00
parent b6554ba2ec
commit 13f470e47d
1 changed files with 6 additions and 3 deletions
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9
src/permutation_argument.rs
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@ -9,6 +9,7 @@ use crate::polynomial::polynomial::PolynomialValues;
use crate::target::Target;
use crate::wire::Wire;
/// Node in the Disjoint Set Forest.
#[derive(Debug, Copy, Clone, Eq, PartialEq)]
pub struct ForestNode<T: Debug + Copy + Eq + PartialEq> {
t: T,
@ -17,9 +18,11 @@ pub struct ForestNode<T: Debug + Copy + Eq + PartialEq> {
index: usize,
}
/// Disjoint Set Forest data-structure following https://en.wikipedia.org/wiki/Disjoint-set_data_structure.
#[derive(Debug, Clone)]
pub struct TargetPartition<T: Debug + Copy + Eq + PartialEq + Hash, F: Fn(T) -> usize> {
forest: Vec<ForestNode<T>>,
/// Function to compute a node's index in the forest.
indices: F,
}
@ -33,6 +36,7 @@ impl<T: Debug + Copy + Eq + PartialEq + Hash, F: Fn(T) -> usize> TargetPartition
/// Add a new partition with a single member.
pub fn add(&mut self, t: T) {
let index = self.forest.len();
debug_assert_eq!((self.indices)(t), index);
self.forest.push(ForestNode {
t,
parent: index,
@ -41,7 +45,7 @@ impl<T: Debug + Copy + Eq + PartialEq + Hash, F: Fn(T) -> usize> TargetPartition
});
}
/// Path halving
/// Path halving method, see https://en.wikipedia.org/wiki/Disjoint-set_data_structure#Finding_set_representatives.
pub fn find(&mut self, mut x: ForestNode<T>) -> ForestNode<T> {
while x.parent != x.index {
let grandparent = self.forest[x.parent].parent;
@ -51,8 +55,7 @@ impl<T: Debug + Copy + Eq + PartialEq + Hash, F: Fn(T) -> usize> TargetPartition
x
}
/// Merge the two partitions containing the two given targets. Does nothing if the targets are
/// already members of the same partition.
/// Merge two sets.
pub fn merge(&mut self, tx: T, ty: T) {
let index_x = (self.indices)(tx);
let index_y = (self.indices)(ty);