Minor AdjacencyGraph Changes

Author: ryanoneill

src/adjacency_graph.rs

@@ -3,21 +3,22 @@ use std::collections::HashSet;
 
 #[derive(Clone, Debug, PartialEq)]
 pub struct AdjacencyGraph {
+    n: usize,
     neighbors: HashMap<i32, HashSet<i32>>,
 }
 
 impl AdjacencyGraph {
 
-    pub fn new() -> Self {
-        Self { neighbors: HashMap::new() }
+    pub fn new(n: usize) -> Self {
+        Self { n, neighbors: HashMap::new() }
     }
 
-    pub fn from_neighbors(neighbors: &HashMap<i32, HashSet<i32>>) -> Self {
-        Self { neighbors: neighbors.clone() }
+    pub fn from_neighbors(n: usize, neighbors: &HashMap<i32, HashSet<i32>>) -> Self {
+        Self { n, neighbors: neighbors.clone() }
     }
 
-    pub fn from_vec(edges: &Vec<Vec<i32>>) -> Self {
-        let mut result = Self::new();
+    pub fn from_vec(n: usize, edges: &Vec<Vec<i32>>) -> Self {
+        let mut result = Self::new(n);
         for edge in edges {
             result.add_edge(edge[0], edge[1]);
         }
@@ -69,7 +70,9 @@ impl AdjacencyGraph {
     }
 
     pub fn find_centroids(&self) -> Vec<i32> {
-        if self.neighbors.len() <= 2 {
+        if self.neighbors.len() == 0 {
+            (0..self.n).into_iter().map(|i| i as i32).collect()
+        } else if self.neighbors.len() <= 2 {
             self.neighbors.keys().copied().collect()
         } else {
             let mut cloned = self.clone();
@@ -93,4 +96,19 @@ impl AdjacencyGraph {
         }
     }
 
+    pub fn vertices_len(&self) -> usize {
+        self.n
+    }
+
+    pub fn edges_len(&self) -> usize {
+        self.neighbors.len()
+    }
+
+    pub fn adj(&self, x: i32) -> HashSet<i32> {
+        self.neighbors
+            .get(&x)
+            .cloned()
+            .unwrap_or(HashSet::new())
+    }
+
 }

src/lib.rs

@@ -92,6 +92,7 @@ pub mod binary_tree_right_side_view; // 199
 pub mod number_of_islands; // 200
 
 pub mod reverse_linked_list; // 206
+pub mod course_schedule; // 207
 
 pub mod contains_duplicate; // 217
 

src/minimum_height_trees.rs

@@ -24,8 +24,9 @@ struct Solution;
 
 impl Solution {
 
-    pub fn find_min_height_tree(_n: i32, edges: Vec<Vec<i32>>) -> Vec<i32> {
-        let graph = AdjacencyGraph::from_vec(&edges);
+    pub fn find_min_height_tree(n: i32, edges: Vec<Vec<i32>>) -> Vec<i32> {
+        let n = n as usize;
+        let graph = AdjacencyGraph::from_vec(n, &edges);
         graph.find_centroids()
     }
 
@@ -52,4 +53,12 @@ mod tests {
         assert_eq!(result, vec![3,4]);
     }
 
+    #[test]
+    fn no_edges() {
+        let n = 1;
+        let edges = vec![];
+        let result = Solution::find_min_height_tree(n, edges);
+        assert_eq!(result, vec![0]);
+    }
+
 }