added Disjkstra's shortest path algorithm

Please pull these things in some time this year. Thank you very much.

Dijsktra_shortest_path.py

@@ -0,0 +1,89 @@
+# Python implementation of Dijkstra's Shortest
+# Path Algorithm. Dijkstra'a algorithm is an
+# algoritm for finding the shortest path between
+# nodes in a weighted graph, which may represent,
+# for example, road networks. It was conceived
+# by computer scientist Edgser Dijkstra in 1956
+# and published three years later. For a given 
+# source node in the graph, the algorithm finds
+# the shortest path between that node and every
+# other node. Dijkstra' algorithm can be used
+# to find the shortest route between one city
+# and all other cities. A widely used application
+# is netowk routing protocols, most notably
+# IS-IS and OSPF. When used with a mininum heap
+# the time complexity is O(E * logV) where E
+# is the number o edges and V is the number
+# of vertices. Space complextiy is O(V). 
+
+
+import heapq
+
+# iPair ==> Integer Pair
+iPair = tuple
+
+# This class represents a directed graph using
+# adjacency list representation
+class Graph:
+	def __init__(self, V: int): # Constructor
+		self.V = V
+		self.adj = [[] for _ in range(V)]
+
+	def addEdge(self, u: int, v: int, w: int):
+		self.adj[u].append((v, w))
+		self.adj[v].append((u, w))
+
+	# Prints shortest paths from src to all other vertices
+	def shortestPath(self, src: int):
+		# Create a priority queue to store vertices that
+		# are being preprocessed
+		pq = []
+		heapq.heappush(pq, (0, src))
+
+		# Create a vector for distances and initialize all
+		# distances as infinite (INF)
+		dist = [float('inf')] * self.V
+		dist[src] = 0
+
+		while pq:
+			# The first vertex in pair is the minimum distance
+			# vertex, extract it from priority queue.
+			# vertex label is stored in second of pair
+			d, u = heapq.heappop(pq)
+
+			# 'i' is used to get all adjacent vertices of a
+			# vertex
+			for v, weight in self.adj[u]:
+				# If there is shorted path to v through u.
+				if dist[v] > dist[u] + weight:
+					# Updating distance of v
+					dist[v] = dist[u] + weight
+					heapq.heappush(pq, (dist[v], v))
+
+		# Print shortest distances stored in dist[]
+		for i in range(self.V):
+                       	print(f"{i} \t\t {dist[i]}")
+
+# Driver's code
+if __name__ == "__main__":
+	# create the graph given in above figure
+	V = 9
+	g = Graph(V)
+
+	# making above shown graph
+	g.addEdge(0, 1, 4)
+	g.addEdge(0, 7, 8)
+	g.addEdge(1, 2, 8)
+	g.addEdge(1, 7, 11)
+	g.addEdge(2, 3, 7)
+	g.addEdge(2, 8, 2)
+	g.addEdge(2, 5, 4)
+	g.addEdge(3, 4, 9)
+	g.addEdge(3, 5, 14)
+	g.addEdge(4, 5, 10)
+	g.addEdge(5, 6, 2)
+	g.addEdge(6, 7, 1)
+	g.addEdge(6, 8, 6)
+	g.addEdge(7, 8, 7)
+
+	g.shortestPath(0)