Add notes for BFS as well

notes-and-examples/2026.07.21/breadth-first-search.md

@@ -0,0 +1,13 @@
+## Breadth-first search (BFS)
+
+In the notes on [depth-first search](./depth-first-search.md), we mention that the difference between DFS and BFS is the order in which nodes are traversed.
+
+Using the same example, what would a breadth-first traversal look like if we start at vertex 0 in this graph?
+
+```
+    0 --- 1
+    |     |
+    3 --- 2
+```
+
+Can we also formalize an algorithm for breadth-first search?

notes-and-examples/2026.07.21/depth-first-search.md

@@ -40,13 +40,7 @@ What about this one?
 
 Based on these examples, can we create a formal algorithm that takes a starting node, producing a valid traversal path for all three graphs?
 
-An example for this graph:
+Some starter questions:
 
-```
-    0 --- 1
-    |     |
-    3 --- 2
-```
-
-- Arguments: starting node `0`
-- Expected output: 
+- Could recursion help us here?
+- What are some ways we can track already-visited nodes? What's the most *time-efficient* way to do so?

notes-and-examples/2026.07.21/overview.md

@@ -1,3 +1,5 @@
 ## Outline
 
-To make our knowledge of graphs useful, we'll go over our first traversal method today: [depth-first search](./depth-first-search.md). If we have time we'll go over breadth-first search, which is the relative to depth-first search.
+To make our knowledge of graphs useful, we'll go over our first traversal method today: [depth-first search](./depth-first-search.md). We will also go over [breadth-first search](./breadth-first-search.md), and how both algorithms can be useful.
+
+Assignment: finish the code for depth-first search, and also implement breadth-first search.