graphalgos/
util.rs

1use std::collections::HashMap;
2use std::hash::Hash;
3
4/// Disjoint Set Definition
5pub struct DisjointSet<T>
6where
7    T: Clone + Eq + Hash,
8{
9    sets: HashMap<T, Vec<T>>,
10    representatives: HashMap<T, T>,
11}
12
13impl<T> DisjointSet<T>
14where
15    T: Clone + Eq + Hash, // Got error coz hashmap value needs these traits
16{
17    /// Associate Function
18    /// Creates a new Disjoint Set
19    ///
20    /// # Example
21    ///
22    /// ```
23    /// let mut set = DisjointSet::new(); // creates a new Disjoint set
24    /// ```
25    pub fn new() -> Self {
26        Self {
27            sets: HashMap::new(),
28            representatives: HashMap::new(),
29        }
30    }
31
32    /// Insert a value to the set
33    ///
34    /// # Example
35    ///
36    /// ```
37    /// // Add all the vertices of graph g to the disjoint set
38    /// for (node, _) in &g.vertices {
39    ///     set.set_insert(node.clone());
40    /// }
41    /// ```
42    pub fn set_insert(&mut self, val: T) {
43        self.sets.insert(val.clone(), vec![val.clone()]);
44        self.representatives.insert(val.clone(), val.clone());
45    }
46
47    /// Find parent of the value
48    ///
49    /// # Example
50    ///
51    /// ```
52    /// set.find(&vertex)
53    /// ```
54    ///
55    pub fn find(&self, val: &T) -> T {
56        self.representatives.get(val).unwrap().clone()
57    }
58
59    /// Union function for two nodes (vertices)
60    ///
61    /// # Example
62    ///
63    /// ```
64    /// set.union(&vertex1, &vertex2)
65    /// ```
66    ///
67    pub fn union(&mut self, a: &T, b: &T) {
68        let repa = self.representatives.get(a).unwrap().clone();
69        let repb = self.representatives.get(b).unwrap().clone();
70        let setb = self.sets.remove(&repb).unwrap(); // get all from set of the second value
71
72        for i in setb.iter() {
73            self.representatives.remove(i); // remove them from their group
74            self.representatives.insert(i.clone(), repa.clone()); // and add them to the first group
75        }
76
77        let seta = self.sets.get_mut(&repa).unwrap();
78
79        // Now all elements from the second set will be added to first and thus union is complete
80        for i in &setb {
81            seta.push(i.clone());
82        }
83    }
84}
graphalgos/util.rs

graphalgos/
util.rs
