Finetune Rust code.

codes/rust/chapter_graph/graph_adjacency_list.rs

@@ -139,4 +139,4 @@ fn main() {
     graph.remove_vertex(v[1]);
     println!("\n删除顶点 3 后，图为");
     graph.print();
-}
+}

codes/rust/chapter_graph/graph_adjacency_matrix.rs

@@ -133,4 +133,4 @@ fn main() {
     graph.remove_vertex(1);
     println!("\n删除顶点 3 后，图为");
     graph.print();
-}
+}

codes/rust/chapter_graph/graph_bfs.rs

@@ -66,4 +66,4 @@ fn main() {
     let res = graph_bfs(graph, v[0]);
     println!("\n广度优先遍历（BFS）顶点序列为");
     println!("{:?}", vets_to_vals(res));
-}
+}

codes/rust/chapter_graph/graph_dfs.rs

@@ -58,4 +58,4 @@ fn main() {
     let res = graph_dfs(graph, v[0]);
     println!("\n深度优先遍历（DFS）顶点序列为");
     println!("{:?}", vets_to_vals(res));
-}
+}