style: include set_contains_or_insert (#797)

Cargo.toml

@@ -167,7 +167,6 @@ suspicious_operation_groupings = { level = "allow", priority = 1 }
 use_self = { level = "allow", priority = 1 }
 while_float = { level = "allow", priority = 1 }
 needless_pass_by_ref_mut = { level = "allow", priority = 1 }
-set_contains_or_insert = { level = "allow", priority = 1 }
 # cargo-lints:
 cargo_common_metadata = { level = "allow", priority = 1 }
 # style-lints:

src/graph/breadth_first_search.rs

@@ -34,8 +34,7 @@ pub fn breadth_first_search(graph: &Graph, root: Node, target: Node) -> Option<V
 
         // Check the neighboring nodes for any that we've not visited yet.
         for neighbor in currentnode.neighbors(graph) {
-            if !visited.contains(&neighbor) {
-                visited.insert(neighbor);
+            if visited.insert(neighbor) {
                 queue.push_back(neighbor);
             }
         }