Add graph references

references/programiz/adj_list.py

@@ -0,0 +1,46 @@
+# Adjascency List representation in Python
+
+
+class AdjNode:
+    def __init__(self, value):
+        self.vertex = value
+        self.next = None
+
+
+class Graph:
+    def __init__(self, num):
+        self.V = num
+        self.graph = [None] * self.V
+
+    # Add edges
+    def add_edge(self, s, d):
+        node = AdjNode(d)
+        node.next = self.graph[s]
+        self.graph[s] = node
+
+        node = AdjNode(s)
+        node.next = self.graph[d]
+        self.graph[d] = node
+
+    # Print the graph
+    def print_agraph(self):
+        for i in range(self.V):
+            print("Vertex " + str(i) + ":", end="")
+            temp = self.graph[i]
+            while temp:
+                print(" -> {}".format(temp.vertex), end="")
+                temp = temp.next
+            print(" \n")
+
+
+if __name__ == "__main__":
+    V = 5
+
+    # Create graph and edges
+    graph = Graph(V)
+    graph.add_edge(0, 1)
+    graph.add_edge(0, 2)
+    graph.add_edge(0, 3)
+    graph.add_edge(1, 2)
+
+    graph.print_agraph()