Create Dijkstra-Algorithm.py

Author: shar2040

python/Dijkstra-Algorithm.py

@@ -0,0 +1,40 @@
+from heapq import *
+from collections import defaultdict
+
+def dijkstra(edges, strat_node, end_node):
+    g = defaultdict(list) 
+    for start, end, weight in edges: 
+        g[start].append((weight, end)) 
+    q, visited = [(0, strat_node,())], set()
+    while q:        
+        (cost,v1,path) = heappop(q)
+        if v1 not in visited:
+            visited.add(v1)
+            path = (v1, path)            
+            if v1 == end_node:
+                return (cost, path)
+            for c, v2 in g.get(v1, ()):
+                if v2 not in visited:
+                    heappush(q, (cost+c, v2, path))
+        print (q)   
+    return float("inf")
+
+if __name__ == "__main__":
+    
+    edges = [
+        ("A", "B", 7),
+        ("A", "D", 5),
+        ("B", "C", 8),
+        ("B", "D", 9),
+        ("B", "E", 7),
+        ("C", "E", 5),
+        ("D", "E", 7),
+        ("D", "F", 6),
+        ("E", "F", 8),
+        ("E", "G", 9),
+        ("F", "G", 11)
+    ]
+    
+    print ("=== Dijkstra ===")
+    print ("A >> G:")
+    print (dijkstra(edges, "A", "G"))