// Source code example for "A Practical Introduction
// to Data Structures and Algorithm Analysis"
// by Clifford A. Shaffer, Prentice Hall, 1998.
// Copyright 1998 by Clifford A. Shaffer

interface Graph {                      // Graph class ADT
  public int n();                      // Number of vertices
  public int e();                      // Number of edges
  public Edge first(int v);            // Get first edge for vertex
  public Edge next(Edge w);            // Get next edge for a vertex
  public boolean isEdge(Edge w);       // True if this is an edge
  public boolean isEdge(int i, int j); // True if this is an edge
  public int v1(Edge w);               // Where edge came from
  public int v2(Edge w);               // Where edge goes to
  public void setEdge(int i, int j, int weight); // Set edge weight
  public void setEdge(Edge w, int weight);       // Set edge weight
  public void delEdge(Edge w);         // Delete edge w
  public void delEdge(int i, int j);   // Delete edge (i, j)
  public int weight(int i, int j);     // Return weight of edge
  public int weight(Edge w);           // Return weight of edge
  public void setMark(int v, int val); // Set Mark for v
  public int getMark(int v);           // Get Mark for v
} // interface Graph