algorithms(bf-to-astar): mention time complexity in BF

Signed-off-by: Matej Focko <me@mfocko.xyz>

algorithms/11-paths/2024-01-01-bf-to-astar/01-bf.md

@@ -387,6 +387,27 @@ possibly look it up, if necessary.
 Also the correctness of the BF relies on the conclusion we've made when fixing
 the infinite-loop on our naïve BF solution.
 
+## Time complexity
+
+Let's have a short look at the time complexities of the presented algorithms:
+
+1. naïve approach: given that there are no negative loops, we are bound by the
+   worst-case ordering of the relaxations which results in
+   $$
+   \mathcal{O}(\vert V \vert \cdot \vert E \vert)
+   $$
+
+2. our naïve approach with the fixed count of iterations instead of the
+   `do-while` loop results in the same worst-case time complexity:
+   $$
+   \mathcal{O}(\vert V \vert \cdot \vert E \vert)
+   $$
+
+3. and finally the well-known Bellman-Ford's algorithm time complexity:
+   $$
+   \mathcal{O}(\vert V \vert \cdot \vert E \vert)
+   $$
+
 ## Small refactor
 
 Since we are literally copy-pasting the body of the loops just for the sake of