Question 3(30p) The figure below shows the structure of a directed graph. Answer the questions based on it. class Vertex class Edge { { }; public int vertexId; public Vertex nextVertex; public Edge edgeLink; graph 1 2 3 m m 2 4 +36/ 2 7 DE 1 2 2 5 }; public int vertexld; public int weight; public Edge nextEdge; edge. Starting vertex is 1, ending vertex is 3 Public Graph copyGraph()//copies the graph Public void restore Graph(Graph g) // restores the graph Public int count() // returns the number of vertices in the graph. Public void topologicalSort(){...} vertex a) Write a method in Graph class that find the neighbors of a given vertex id.(10p) b) Write a method that will do topological sort(display vertex ids. You do not have keep them) on the graph. Your method will be in the Graph class. The following methods are implemented for you to use incase you need them. (20p) Public Vertex findVertexIndegreeZero()//finds and return a vertex with an indegree of zero Public bool checkCycle() // checks whether the graph has a cycle or not