Update shortest-cycle-in-a-graph.py

Author: kamyu104

Python/shortest-cycle-in-a-graph.py

@@ -22,11 +22,11 @@ def bfs(u):
                         if dist[v] != INF:
                             assert(abs(dist[v]-dist[u]) <= 1)
                             if dist[v] != dist[u]-1:
-                                result = min(result, 1+dist[u]+dist[v])
+                                result = min(result, 1+dist[u]+dist[v])  # d = dist[u]+1 >= 2, check if any cycle of length 2*d-1 or 2*d exists
                             continue
                         dist[v] = dist[u]+1
                         new_q.append(v)
-                if result != INF:
+                if result != INF:  # a cycle of length 2*d-1 or 2*d was found, early return
                     break
                 q = new_q
             return result