detect cycles and use usize for most numbers

src/graph.rs

@@ -8,7 +8,7 @@ struct Edgenode {
     #[allow(unused)]
     weight: i32, // Edge weight, if any
 
-    y: i32,                     // Adjacency info
+    y: usize,                     // Adjacency info
     next: Option<Rc<Edgenode>>, // next edge in list
 }
 
@@ -16,7 +16,7 @@ pub struct Graph {
     edges: Vec<Option<Rc<Edgenode>>>, // adjacency info
     degree: Vec<i32>,                 // outdegree of each vertex
     nvertices: usize,                 // number of vertices in graph
-    nedges: i32,                      // number of edges in graph
+    nedges: usize,                      // number of edges in graph
     directed: bool,                   // is the graph directed?
 }
 
@@ -26,8 +26,10 @@ struct SearchState {
     // A vertex is `processed` after we have traversed all outgoing
     // edges from it.
     processed: Vec<bool>,
-    // Discovery relation
+    // Discovery relation. Needs to be signed cause we initialize it to -1
     parent: Vec<i32>,
+    // Time tracking for DFS
+    time: usize,
 }
 
 impl Graph {
@@ -41,7 +43,7 @@ impl Graph {
         }
     }
 
-    fn insert_edge(&mut self, x: usize, y: i32, directed: bool) {
+    fn insert_edge(&mut self, x: usize, y: usize, directed: bool) {
         let p = Rc::new(Edgenode {
             y,
             weight: 0,
@@ -52,7 +54,7 @@ impl Graph {
         if directed {
             self.nedges += 1;
         } else {
-            self.insert_edge(y.try_into().unwrap(), x.try_into().unwrap(), true);
+            self.insert_edge(y, x, true);
         }
     }
 
@@ -83,9 +85,9 @@ impl Graph {
 
         // After that, parse edges as (x, y)
         for _ in 0..num_edges {
-            let x: i32 = data_parsed.pop().unwrap().parse().unwrap();
-            let y: i32 = data_parsed.pop().unwrap().parse().unwrap();
-            self.insert_edge(x.try_into().unwrap(), y, directed);
+            let x: usize = data_parsed.pop().unwrap().parse().unwrap();
+            let y: usize = data_parsed.pop().unwrap().parse().unwrap();
+            self.insert_edge(x, y, directed);
         }
     }
 
@@ -99,7 +101,7 @@ impl Graph {
             state.processed[v] = true;
             let mut p_opt = &self.edges[v];
             while let Some(p) = p_opt {
-                let y: usize = p.y.try_into().unwrap();
+                let y: usize = p.y;
                 if !state.processed[y] || self.directed {
                     println!("process edge ({:?},{:?})", v, y);
                 }
@@ -122,7 +124,7 @@ impl Graph {
         while let Some(v) = q.pop() {
             let mut p_opt = &self.edges[v];
             while let Some(p) = p_opt {
-                let y: usize = p.y.try_into().unwrap();
+                let y: usize = p.y;
                 if !state.discovered[y] {
                     state.discovered[y] = true;
                     state.parent[y] = v.try_into().unwrap();
@@ -131,6 +133,9 @@ impl Graph {
                 } else if !state.processed[y] || self.directed {
                     println!("process edge ({:?},{:?})", v, y);
                 }
+                if state.parent[y] != v.try_into().unwrap() {
+                    println!("cycle from {:?} to {:?}", v, y);
+                }
                 p_opt = &p.next;
             }
             state.processed[v] = true;
@@ -144,6 +149,7 @@ impl SearchState {
             discovered: vec![false; MAXV],
             processed: vec![false; MAXV],
             parent: vec![-1; MAXV],
+            time: 0,
         }
     }
 }