Gale-Shapley implementation in Rust

CONTRIBUTORS.md

@@ -50,3 +50,4 @@ This file lists everyone, who contributed to this repo and wanted to show up her
 - Akash Dhiman
 - Vincent Zalzal
 - Jonathan D B Van Schenck
+- Ishaan Verma

contents/stable_marriage_problem/code/rust/stable_marriage.rs

@@ -0,0 +1,107 @@
+use std::vec::Vec;
+use std::collections::HashMap;
+use std::fmt;
+
+#[derive(Hash, Eq, PartialEq, Copy, Clone)]
+struct PersonId(pub char);
+
+impl fmt::Display for PersonId {
+    fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
+        write!(f, "{}", self.0)
+    }
+}
+
+#[derive(Clone)]
+struct Person {
+    id: PersonId,
+    partner: Option<PersonId>,
+    preferences: Vec<PersonId>,
+}
+
+fn gale_shapley(people: Vec<Person>) -> HashMap<PersonId, PersonId> {
+    let mut stable_matching: HashMap<PersonId, PersonId> = HashMap::new();
+
+    for person in people {
+        let partner = stable_matching
+            .get(&person.id)
+            .or_else(||     // execute this if person doesn't have partner
+                person.preferences
+                .iter()
+                // skip all preferences which already have a pair
+                .skip_while(|id| stable_matching.contains_key(id))
+                .next()
+            )
+            .map(|&id| id);
+
+        if let Some(partner) = partner {    // set partner
+            stable_matching.insert(person.id, partner);
+            stable_matching.insert(partner, person.id);
+        }
+    }
+    stable_matching
+}
+
+fn main() {
+    // create men vector
+    let men: Vec<Person> = vec![
+        ('A', vec!['E', 'G', 'F', 'H']),
+        ('B', vec!['F', 'H', 'E', 'F']),
+        ('C', vec!['F', 'E', 'H', 'G']),
+        ('D', vec!['E', 'H', 'F', 'G'])
+    ]
+    .into_iter()
+    .map(|(id, pref)|
+        Person {
+            id: PersonId(id),
+            partner: None,
+            preferences: pref.into_iter().map(PersonId).collect(),
+        }
+    ).collect();
+
+    // create women vector
+    let women: Vec<Person> = vec![
+        ('E', vec!['A', 'D', 'C', 'B']),
+        ('F', vec!['D', 'B', 'A', 'C']),
+        ('G', vec!['D', 'A', 'C', 'B']),
+        ('H', vec!['B', 'A', 'D', 'C'])
+    ]
+    .into_iter()
+    .map(|(id, pref)|
+        Person {
+            id: PersonId(id),
+            partner: None,
+            preferences: pref.into_iter().map(PersonId).collect(),
+        }
+    ).collect();
+
+    let people: Vec<Person> = men.iter().cloned().chain(
+        women.iter().cloned()).collect();
+
+    println!("Men: \n");
+    for man in &men {
+        println!("\t{}: {:?}", man.id, man.preferences.clone()
+            // convert men.preference to vector of chars
+            .into_iter()
+            .map(|person| person.0)
+            .collect::<Vec<char>>());
+    }
+    println!("Women: \n");
+    for woman in &women {
+        println!("\t{}: {:?}", woman.id, woman.preferences.clone()
+            // convert women.preference to vector of chars
+            .into_iter()
+            .map(|person| person.0)
+            .collect::<Vec<char>>());
+    }
+
+    let stable_matching: HashMap<PersonId, PersonId> = gale_shapley(people);
+
+    // display stable matches
+    for man in men {
+        let partner_id = stable_matching.get(&man.id);
+        match partner_id {
+            Some(p) => println!("{} + {}", man.id, p),
+            None => ()
+        }
+    }
+}

contents/stable_marriage_problem/stable_marriage_problem.md

@@ -58,6 +58,8 @@ Here is a video describing the stable marriage problem:
 [import, lang:"php"](code/php/stable_marriage.php)
 {% sample lang="scala" %}
 [import, lang:"scala"](code/scala/stable_marriage.scala)
+{% sample lang="rust" %}
+[import, lang:"rust"](code/rust/stable_marriage.rs)
 {% endmethod %}
 
 <script>