import java.util.Scanner;
import java.io.File;
import java.io.FileNotFoundException;

/* Java application that reads a description of an outdegree-1 graph from 
** a file (whose name is provided via command line argument) and then, for 
** each node v in the graph, displays (the IDs of) the nodes
** 
** (1) that lie on the cycle that is reached by v, and
** (2) that lie on the path from v to the closest node on that cycle.
**
** Authors: R. McCloskey and < STUDENTS' NAMES >
** Known Defects: ...
*/
public class PathsApp {

   private static OutDeg1Graph graph;  // the graph being examined

   public static void main(String[] args) {
      // args[0] is assumed to be name of a file containing the description
      // of an outdegree-1 graph.
      graph = readGraph(args[0]);

      System.out.println("The graph:");
      System.out.println(graph);

      final int N = graph.numNodes();
      for (int v = 0; v != N; v++) {
         System.out.printf("\nCycle reached by node %d: ", v);
         cycleReachedBy(v);

         System.out.printf("Path to cycle from node %d: ", v);
         pathToCycle(v);
      }

   }

   /* Displays the (ID's of the) nodes that lie on the cycle 
   ** reached by the specified node.  
   ** Note: The order in which the nodes are displayed is going 
   ** backwards around the cycle.
   */
   public static void cycleReachedBy(int v) {
      // STUB!
   }

   /* Displays the (ID's of the) nodes that lie on the path from the 
   ** specified node to the "first" node lying on the cycle that it reaches.
   ** (If the node itself lies on a cycle, it should be the lone node whose
   ** ID is displayed.)
   ** Note: The order in which the nodes are displayed goes backwards to v.
   */
   public static void pathToCycle(int v) {
      // STUB!
   }


   /* Returns an OutDeg1Graph object that corresponds to the outdegree-1
   ** graph described in the file having the given name.
   ** The expected format for a plain text description of an outdegree-1 
   ** graph is exemplified by the following, which describes a graph of 
   ** six nodes (as indicated by the first numeral) in which the single 
   ** outgoing edge from nodes 0, 1, ..., 5 go to nodes 2, 0, 4, 2, 5,
   ** and 1, respectively.
   ** +--------------+
   ** |6 2 0 4 2 5 1 |
   ** +--------------+
   */
   private static OutDeg1Graph readGraph(String fileName) {
      try {
         Scanner input = new Scanner(new File(fileName));
         int numNodes = input.nextInt();
         int[] arcs = new int[numNodes];
         for (int i=0; i != numNodes; i++) {
            arcs[i] = input.nextInt();
         }
         return new OutDeg1Graph(arcs);
     }
     catch (Exception e) {
         e.printStackTrace(System.out);
         System.out.println("\nProgram aborting");
         System.exit(0);
     }
     return null;  // compiler requires a return statement here, even 
   }               // though it cannot be reached

}