Added Dijkstra's single source shortest paths algorithm

Author: KyattPL

data-structures/WeightedGraph.py

@@ -29,6 +29,47 @@ def kruskal(self):
                 forest.union(edge[0], edge[1])
         return ans
 
+    def edge_exists(self, start, vertex):
+        for edge in self.edges:
+            if start == edge[0] and vertex == edge[1]:
+                return (True, edge[2])
+        return (False, -1)
+
+    def minimum_dist(self, distance, visited):
+        minimum = float("inf")
+        min_index = -1
+        for vert in self.vertices:
+            if distance[vert] < minimum and vert not in visited:
+                minimum = distance[vert]
+                min_index = vert
+
+        return min_index
+
+    def get_weight(self, start, end):
+        for edge in self.edges:
+            if start == edge[0] and end == edge[1]:
+                return edge[2]
+        return float("inf")
+
+    def dijkstra_single_source(self, start):
+        visited = []
+        distance = [0] * len(self.vertices)
+        for vertex in self.vertices:
+            (exists, weight) = self.edge_exists(start, vertex)
+            if vertex != start and exists:
+                distance[vertex] = weight
+            else:
+                distance[vertex] = float("inf")
+        while len(visited) != len(self.vertices):
+            u = self.minimum_dist(distance, visited)
+            visited.append(u)
+            for vert in self.vertices:
+                if vert not in visited:
+                    distance[vert] = min(
+                        distance[vert], distance[u] + self.get_weight(u, vert))
+
+        print(distance)
+
 
 if __name__ == "__main__":
     g = WeightedGraph()
@@ -43,3 +84,4 @@ def kruskal(self):
     g.add_edge(4, 5, 5)
     g.add_edge(5, 6, 3)
     print(g.kruskal())
+    g.dijkstra_single_source(0)