From 14a3342f60e5c2b631e7fe1b9007961a4b77d606 Mon Sep 17 00:00:00 2001
From: mxhagen <markichnich@proton.me>
Date: Sun, 16 Feb 2025 19:25:00 +0100
Subject: [PATCH] add graph! macro and vertex/edge_count

---
 src/graph.rs | 34 +++++++++++++++++++++++++++++-----
 src/main.rs  | 42 +++++++++++++++++++++---------------------
 2 files changed, 50 insertions(+), 26 deletions(-)

diff --git a/src/graph.rs b/src/graph.rs
index a43e081..6a6407d 100644
--- a/src/graph.rs
+++ b/src/graph.rs
@@ -4,7 +4,7 @@ use std::{
 };
 
 pub struct Graph<V> {
-    pub vertices: Vec<V>,
+    pub vertices: HashSet<V>,
     pub edges: HashMap<V, Vec<V>>,
 }
 
@@ -12,6 +12,16 @@ impl<V> Graph<V>
 where
     V: Eq + Hash + Ord + Clone,
 {
+    /// get the number of vertices of the graph
+    pub fn vertex_count(&self) -> usize {
+        self.vertices.len()
+    }
+
+    /// get the number of edges of the graph
+    pub fn edge_count(&self) -> usize {
+        self.edges.values().map(Vec::len).sum()
+    }
+
     /// check if an edge is contained in the graph
     /// (only checks the provided direction)
     pub fn has_edge(&self, edge: (&V, &V)) -> bool {
@@ -49,8 +59,7 @@ where
         q.push_back(vec![from]);
         visited.insert(from);
 
-        while !q.is_empty() {
-            let mut path = q.pop_front().unwrap();
+        while let Some(mut path) = q.pop_front() {
             let current = path.last().unwrap();
 
             for neighbor in self.neighbors(current) {
@@ -81,8 +90,7 @@ where
 
         q.push(vec![from]);
 
-        while !q.is_empty() {
-            let mut path = q.pop().unwrap();
+        while let Some(mut path) = q.pop() {
             let &current = path.last().unwrap();
 
             if current == to {
@@ -103,3 +111,19 @@ where
         None
     }
 }
+
+#[macro_export]
+macro_rules! graph {
+    ( $( $v:tt : $( $e:tt ),* );* $(;)? ) => {{
+        let mut edges = std::collections::HashMap::new();
+        let mut vertices = std::collections::HashSet::new();
+
+        $(
+            vertices.insert($v);
+            edges.insert($v, vec![$( $e ),*]);
+            $( vertices.insert($e); )*
+        )*
+
+        Graph { vertices, edges }
+    }};
+}
diff --git a/src/main.rs b/src/main.rs
index 47e65a9..d2f4d9d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -1,5 +1,3 @@
-use std::collections::HashMap;
-
 mod graph;
 pub use graph::Graph;
 
@@ -9,24 +7,18 @@ fn main() {
     //   -> 0     ┃     3
     //      ┗━━━━━2━━━━━┛
 
-    let vs = vec![0, 1, 2, 3];
-    let es = HashMap::from([
-        (0, vec![1, 2]),
-        (1, vec![0, 2, 3]),
-        (2, vec![0, 1, 3]),
-        (3, vec![1, 2]),
-    ]);
-
-    let g = Graph {
-        vertices: vs.clone(),
-        edges: es.clone(),
+    let g = graph! {
+        0: 1, 2;
+        1: 0, 2, 3;
+        2: 0, 1, 3;
+        3: 1, 2;
     };
 
-    for v in &vs {
+    for v in &g.vertices {
         assert!(g.has_vertex(v), "G should contain vertex {v}");
     }
 
-    for (a, neighbors) in &es {
+    for (a, neighbors) in &g.edges {
         for b in neighbors {
             assert!(g.has_edge((a, b)), "G should contain edge ({a}, {b})");
             assert!(
@@ -36,19 +28,27 @@ fn main() {
         }
     }
 
-    for i in 0..vs.len() {
-        for j in i + 1..vs.len() {
+    let n = g.vertex_count();
+    let vs = g.vertices.iter().collect::<Vec<_>>();
+    for i in 0..n {
+        for j in i + 1..n {
             let (a, b) = (vs[i], vs[j]);
             let shortest_path_length = match (a, b) {
                 (0, 3) | (3, 0) => 3,
                 _ => 2,
             };
 
-            let path = g.find_path_dfs(&a, &b);
-            assert!(path.is_some(), "Path from {a} to {b} should be found in G with dfs");
+            let path = g.find_path_dfs(a, b);
+            assert!(
+                path.is_some(),
+                "Path from {a} to {b} should be found in G with dfs"
+            );
 
-            let path = g.find_path_bfs(&a, &b);
-            assert!(path.is_some(), "Path from {a} to {b} should be found in G with bfs");
+            let path = g.find_path_bfs(a, b);
+            assert!(
+                path.is_some(),
+                "Path from {a} to {b} should be found in G with bfs"
+            );
 
             let path = path.unwrap();
             assert_eq!(