added dijkstras with test pass

src/dijkstras.rs

@@ -1,42 +1,46 @@
-use std::collections::{HashMap, HashSet};
+use std::collections::HashMap;
 
 #[cfg(test)]
 mod tests {
-    use super::dijkstras_shortest_path;
+    use super::{dijkstras_shortest_path,WeightedAdjacencyList};
     #[test]
     fn dijkstras_shortest_path_primeagen_class_test(){
-        //      (B) --- (E) ---- (F)
+        //      (1) --- (4) ---- (5)
         //    /  |       |       /|
-        // (A)   | ------|------- |
+        // (0)   | ------|------- |
         //    \  |/      |        |
-        //      (C) --- (D) ---- (G)
+        //      (2) --- (3) ---- (6)
-        let mut graph:WeightedAdjacencyList<&str,usize> = WeightedAdjacencyList::new();
+        let source = 0;
-        graph.add_vertex("A");
+        let sink = 5;
-        graph.add_vertex("B");
+
-        graph.add_vertex("C");
+        let mut graph:WeightedAdjacencyList<usize,usize> = WeightedAdjacencyList::new();
-        graph.add_vertex("D");
+        graph.add_vertex(0);
-        graph.add_vertex("E");
+        graph.add_vertex(1);
-        graph.add_vertex("F");
+        graph.add_vertex(2);
-        graph.add_edge("A","B",3);
+        graph.add_vertex(3);
-        graph.add_edge("A","C",1);
+        graph.add_vertex(4);
-        graph.add_edge("B","A",3);
+        graph.add_vertex(5);
-        graph.add_edge("B","C",4);
+        graph.add_edge(0, 1, 3);
-        graph.add_edge("B","E",1);
+        graph.add_edge(0, 2, 1);
-        graph.add_edge("C","B",4);
+        graph.add_edge(1, 0, 3);
-        graph.add_edge("C","D",7);
+        graph.add_edge(1, 2, 4);
-        graph.add_edge("C","A",1);
+        graph.add_edge(1, 4, 1);
-        graph.add_edge("D","C",7);
+        graph.add_edge(2, 1, 4);
-        graph.add_edge("D","E",5);
+        graph.add_edge(2, 3, 7);
-        graph.add_edge("D","G",1);
+        graph.add_edge(2, 0, 1);
-        graph.add_edge("E","B",1);
+        graph.add_edge(3, 2, 7);
-        graph.add_edge("E","D",5);
+        graph.add_edge(3, 4, 5);
-        graph.add_edge("E","F",2);
+        graph.add_edge(3, 6, 1);
-        graph.add_edge("F","G",1);
+        graph.add_edge(4, 1, 1);
-        graph.add_edge("F","E",2);
+        graph.add_edge(4, 3, 5);
-        graph.add_edge("F","C",18);
+        graph.add_edge(4, 5, 2);
-        graph.add_edge("G","D",1);
+        graph.add_edge(5, 6, 1);
-        graph.add_edge("G","F",1);
+        graph.add_edge(5, 4, 2);
-        dijkstras_shortest_path(source,sink,graph);
+        graph.add_edge(5, 2, 18);
+        graph.add_edge(6, 3, 1);
+        graph.add_edge(6, 5, 1);
+        let path = dijkstras_shortest_path(source,sink,graph.clone());
+        assert_eq!(path.unwrap(), vec![0, 1, 4, 5]);
     }
 }
 // Define a struct to represent the adjacency list with weighted edges
@@ -44,6 +48,18 @@ pub struct WeightedAdjacencyList<T, W> {
     vertices: HashMap<T, HashMap<T, W>>,
 }
 
+impl<T, W> Clone for WeightedAdjacencyList<T, W>
+where
+    T: Clone,
+    W: Clone,
+{
+    fn clone(&self) -> Self {
+        WeightedAdjacencyList {
+            vertices: self.vertices.clone(),
+        }
+    }
+}
+
 impl<T, W> WeightedAdjacencyList<T, W>
 where
     T: std::hash::Hash + Eq + Clone,
@@ -79,24 +95,65 @@ where
     fn get_neighbors(&self, vertex: &T) -> Option<&HashMap<T, W>> {
         self.vertices.get(vertex)
     }
+    // Method to get the number of vertices in the adjacency list
+    fn len(&self) -> usize {
+        self.vertices.len()
     }
+}
+pub fn dijkstras_shortest_path(
+    source: usize,
+    sink: usize,
+    graph: WeightedAdjacencyList<usize, usize>,
+) -> Option<Vec<usize>> {
+    let mut seen: Vec<bool> = vec![false; graph.len()];
+    let mut prev: Vec<usize> = vec![usize::MAX; graph.len()];
+    let mut dists: Vec<f64> = vec![f64::INFINITY; graph.len()];
+    dists[source] = 0.0;
+
+    while has_unvisited(&seen, &dists) {
+        let curr = get_lowest_unvisited(&seen, &dists);
+        seen[curr] = true;
+        if let Some(adjs) = graph.get_neighbors(&curr) {
+            for (&to, &weight) in adjs.iter() {
+                if !seen[to] {
+                    let new_dist = dists[curr] + weight as f64;
+                    if new_dist < dists[to] {
+                        dists[to] = new_dist;
+                        prev[to] = curr;
+                    }
+                }
+            }
+        }
+    }
+
+    // Check if sink is unreachable
+    if prev[sink] == usize::MAX {
+        return None;
+    }
+
+    // Reconstruct shortest path
+    let mut path = Vec::new();
+    let mut curr = sink;
+    while curr != usize::MAX {
+        path.push(curr);
+        curr = prev[curr];
+    }
+    path.reverse();
+    Some(path)
+}
+
 fn has_unvisited(seen: &[bool], dists: &[f64]) -> bool {
-    return seen.iter().enumerate().any(|(i, &s)| !s && dists[i] < f64::INFINITY);
+    seen.iter().enumerate().any(|(i, &s)| !s && dists[i] < f64::INFINITY)
 }
+
 fn get_lowest_unvisited(seen: &[bool], dists: &[f64]) -> usize {
     let mut idx = usize::MAX;
     let mut lowest_distance = f64::INFINITY;
     for (i, &is_seen) in seen.iter().enumerate() {
-        if is_seen {
+        if !is_seen && dists[i] < lowest_distance {
-            continue;
-        }
-        if lowest_distance > dists[i] {
             lowest_distance = dists[i];
             idx = i;
         }
     }
     idx
 }
-pub fn dijkstras_shortest_path(source:usize,sink:usize,mut graph:WeightedAdjacencyList<&str,usize>){
-    
-}