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 +1,136 @@
+#[derive(Eq, PartialEq, PartialOrd)]
+struct Person {
+    name: char,     // a single character denoting the person e.g 'A', 'B', 'F'
+    index: usize,   // index in men/women vecotr
+    preference: Vec<usize>,
+    pref_index: usize,
+    candidates: Vec<usize>, // all those men/women who have proposed to self
+    partner: Option<usize>
+}
+
+impl Person {
+    fn propose_to_next(&mut self, women: &mut Vec<Person>) {
+        /* propose to next most preferred person */
+
+        if self.pref_index >= self.preference.len() {
+            ()
+        }
+
+        let person = self.preference[self.pref_index];
+        // add self to the preferred woman's candidates
+        women[person].candidates.push(self.index);
+
+        self.pref_index += 1;
+
+    }
+
+    fn pick_preferred(&mut self, men: &mut Vec<Person>) {
+        /* pick the highest preferred man among candidates */
+
+        for person in &self.preference {
+            if Some(*person) == self.partner {
+                break
+            } else if self.candidates.contains(&person) {
+                match self.partner {
+                    Some(ind) => {
+                        // If self currently has a partner, set self's partner's partner to None
+                        men[ind].partner = None;
+                    },
+                    None => {
+                        self.partner = Some(*person);
+                        men[*person].partner = Some(self.index);
+                    }
+                }
+                break
+            }
+        }
+    }
+
+}
+
+fn init_person(name: char, index: usize, pref: Vec<usize>) -> Person {
+    let person = Person {
+        name: name,
+        index: index,
+        preference: pref,
+        pref_index: 0,
+        candidates: Vec::new(),
+        partner: None
+    };
+    person
+}
+
+fn main() {
+    let mut men = vec![
+        init_person('A', 0, vec![1, 0, 3, 2]),
+        init_person('B', 1, vec![3, 0, 2, 1]),
+        init_person('C', 2, vec![2, 3, 1, 0]),
+        init_person('D', 3, vec![1, 2, 0, 3])
+    ];
+
+    let mut women = vec![
+        init_person('E', 0, vec![3, 2, 0, 1]),
+        init_person('F', 1, vec![0, 2, 1, 3]),
+        init_person('G', 2, vec![0, 1, 2, 3]),
+        init_person('H', 3, vec![2, 0, 1, 3])
+    ];
+
+    println!("Men: ");
+    for man in &men {
+        println!("\t{}, preference = {:?}", man.name, {
+            let mut vect: Vec<char> = Vec::new();
+            for man in &man.preference {
+                vect.push(women[*man].name);
+            }
+            vect
+        });
+    }
+
+    println!("Women: ");
+    for woman in &women {
+        println!("\t{}, preference = {:?}", woman.name, {
+            let mut vect: Vec<char> = Vec::new();
+            for woman in &woman.preference {
+                vect.push(men[*woman].name);
+            }
+            vect
+        });
+    }
+
+
+    /* Resolve */
+    let mut cont = true;
+    while cont {
+        // Each man proposes to his highest preference
+        for man in &mut men {
+            if man.partner.is_none() {
+                man.propose_to_next(&mut women);
+            }
+        }
+
+        // Each woman picks here highest preference
+        for woman in &mut women {
+            woman.pick_preferred(&mut men);
+        }
+
+        // If there is a single man who does not have a partner, continue resolving
+        cont = false;
+        for man in &men {
+            if man.partner.is_none() {
+                cont = true;
+                break;
+            }
+        }
+    }
+
+    println!("\nStable Matching: ");
+    for man in &men {
+        match man.partner {
+            Some(p) => {
+                println!("\t{} + {}", man.name, women[p].name);
+            },
+            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>