/* bfs-dfs.c A generic implementation of graph traversal: breadth-first and depth-first search begun: March 27, 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" #include "queue.h" bool processed[MAXV]; /* which vertices have been processed */ bool discovered[MAXV]; /* which vertices have been found */ int parent[MAXV]; /* discovery relation */ bool finished = FALSE; /* if true, cut off search immediately */ initialize_search(graph *g) { int i; /* counter */ for (i=1; i<=g->nvertices; i++) { processed[i] = discovered[i] = FALSE; parent[i] = -1; } } bfs(graph *g, int start) { queue q; /* queue of vertices to visit */ int v; /* current vertex */ int i; /* counter */ init_queue(&q); enqueue(&q,start); discovered[start] = TRUE; while (empty(&q) == FALSE) { v = dequeue(&q); process_vertex(v); processed[v] = TRUE; for (i=0; idegree[v]; i++) if (valid_edge(g->edges[v][i]) == TRUE) { if (discovered[g->edges[v][i]] == FALSE) { enqueue(&q,g->edges[v][i]); discovered[g->edges[v][i]] = TRUE; parent[g->edges[v][i]] = v; } if (processed[g->edges[v][i]] == FALSE) process_edge(v,g->edges[v][i]); } } } /* bool valid_edge(edge e) { if (e.residual > 0) return (TRUE); else return(FALSE); } */ dfs(graph *g, int v) { int i; /* counter */ int y; /* successor vertex */ if (finished) return; /* allow for search termination */ discovered[v] = TRUE; process_vertex(v); for (i=0; idegree[v]; i++) { y = g->edges[v][i]; if (valid_edge(g->edges[v][i]) == TRUE) { if (discovered[y] == FALSE) { parent[y] = v; dfs(g,y); } else if (processed[y] == FALSE) process_edge(v,y); } if (finished) return; } processed[v] = TRUE; } find_path(int start, int end, int parents[]) { if ((start == end) || (end == -1)) printf("\n%d",start); else { find_path(start,parents[end],parents); printf(" %d",end); } }