Corrected wrong Dijkstra priority queue implementation (#909)

ziyzhu · poyea · commit a212efee5b44 · 2019-06-23T23:32:12.000+08:00
* Corrected wrong DFS implementation

* changed list into hash set for dijkstra priority queue implementation.
diff --git a/graphs/dijkstra.py b/graphs/dijkstra.py
@@ -20,12 +20,12 @@
 
 def dijkstra(graph, start, end):
     heap = [(0, start)]  # cost from start node,end node
-    visited = []
+    visited = set()
     while heap:
         (cost, u) = heapq.heappop(heap)
         if u in visited:
             continue
-        visited.append(u)
+        visited.add(u)
         if u == end:
             return cost
         for v, c in G[u]:
