/* findcycle.c
Identify a cycle in a graph, if one exists.
begun: March 6, 2002
by: Steven Skiena
*/
/*
Copyright 2003 by Steven S. Skiena; all rights reserved.
Permission is granted for use in non-commerical applications
provided this copyright notice remains intact and unchanged.
This program appears in my book:
"Programming Challenges: The Programming Contest Training Manual"
by Steven Skiena and Miguel Revilla, Springer-Verlag, New York 2003.
See our website www.programming-challenges.com for additional information.
This book can be ordered from Amazon.com at
http://www.amazon.com/exec/obidos/ASIN/0387001638/thealgorithmrepo/
*/
#include "bool.h"
#include "graph.h"
extern bool processed[]; /* which vertices have been processed */
extern bool discovered[]; /* which vertices have been found */
extern int parent[]; /* discovery relation */
extern bool finished; /* flag for early search cutoff */
process_vertex_early(int v)
{
}
process_vertex_late(int v)
{
}
process_edge(int x, int y)
{
if (parent[x] != y) { /* found back edge! */
printf("Cycle from %d to %d:",y,x);
find_path(y,x,parent);
printf("\n\n");
finished = TRUE;
}
}
main()
{
graph g;
int i;
read_graph(&g,FALSE);
print_graph(&g);
initialize_search(&g);
dfs(&g,1);
}