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authorKatolaZ <katolaz@freaknet.org>2017-09-27 15:06:31 +0100
committerKatolaZ <katolaz@freaknet.org>2017-09-27 15:06:31 +0100
commit3aee2fd43e3059a699af2b63c6f2395e5a55e515 (patch)
tree58c95505a0906ed9cfa694f9dbd319403fd8f01d /src/dijkstra/dijkstra.c
First commit on github -- NetBunch 1.0
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diff --git a/src/dijkstra/dijkstra.c b/src/dijkstra/dijkstra.c
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+/**
+ * This program is free software: you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see
+ * <http://www.gnu.org/licenses/>.
+ *
+ * (c) Vincenzo Nicosia 2009-2017 -- <v.nicosia@qmul.ac.uk>
+ *
+ * This file is part of NetBunch, a package for complex network
+ * analysis and modelling. For more information please visit:
+ *
+ * http://www.complex-networks.net/
+ *
+ * If you use this software, please add a reference to
+ *
+ * V. Latora, V. Nicosia, G. Russo
+ * "Complex Networks: Principles, Methods and Applications"
+ * Cambridge University Press (2017)
+ * ISBN: 9781107103184
+ *
+ ***********************************************************************
+ *
+ *
+ * This program implements the Dijkstra's algorithm to find the
+ * shortest paths from a given node (source) to all the other nodes
+ * of a weighted graph given as input.
+ *
+ * References:
+ *
+ * [1] E. W. Dijkstra. "A Note on Two Problems in Connexion with
+ * Graphs". Num. Math. 1 (1959), 269-271.
+ *
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <float.h>
+
+#include "utils.h"
+#include "gen_pqueue.h"
+
+#include "node_w_funs.h"
+
+#define INFINITY DBL_MAX
+
+
+void usage(char *argv[]){
+ printf("********************************************************************\n"
+ "** **\n"
+ "** -*- dijkstra -*- **\n"
+ "** **\n"
+ "** Compute the distance from the given 'node' to all the other **\n"
+ "** nodes of a weighted graph. The first parameter 'graph_in' **\n"
+ "** is the name of the file containing the edge list of the **\n"
+ "** graph. The second parameter 'node' is the label of the node **\n"
+ "** for which we want to compute the distances to all the other **\n"
+ "** nodes. **\n"
+ "** **\n"
+ "** If 'graph_in' is equal to '-' (dash), read the edge list **\n"
+ "** from standard input (STDIN) **\n"
+ "** **\n"
+ "** The program prints on output a row of values: **\n"
+ "** **\n"
+ "** d0 d1 d2 d3 d4...... **\n"
+ "** **\n"
+ "** where d0 is the distance between 'node' and '0', 'd1' is the **\n"
+ "** distance between 'node' and '1', and so on. If a node is **\n"
+ "** not reachable from <node>, the corresponding distance is set **\n"
+ "** to 'inf'. **\n"
+ "** **\n"
+ "** **\n"
+ "********************************************************************\n"
+ " This is Free Software - You can use and distribute it under \n"
+ " the terms of the GNU General Public License, version 3 or later\n\n"
+ " Please visit http://www.complex-networks.net for more information\n\n"
+ " (c) Vincenzo Nicosia 2010-2017 (v.nicosia@qmul.ac.uk)\n"
+ "********************************************************************\n\n"
+ );
+ printf("Usage: %s <graph_in> <node>\n\n" , argv[0]);
+}
+
+
+
+void init_prio_queue(gen_pqueue_t **q, unsigned int N){
+
+ gen_pqueue_func_t *funs;
+
+ funs = malloc(sizeof(gen_pqueue_func_t));
+ (*funs).compare = compare_node_w;
+ (*funs).alloc_vector = alloc_vector_node_w;
+ (*funs).dealloc_vector = dealloc_vector_node_w;
+ (*funs).dealloc_elem = dealloc_elem_node_w;
+ (*funs).print_elem = print_elem_node_w;
+ (*funs).get_id = get_id_node_w;
+ (*funs).set_key = set_key_node_w;
+ (*funs).get_key = get_key_node_w;
+ (*funs).compare_to_key = compare_to_key_node_w;
+
+ *q = gen_pqueue_init(N, MIN_QUEUE, funs);
+ free(funs);
+}
+
+void flatten_pqueue_to_array(gen_pqueue_t *q, double *v, unsigned int N){
+
+ int i;
+ double *val;
+
+ for(i=0; i<N; i++){
+ val = gen_pqueue_get_key(q, gen_pqueue_get_handle(q, i));
+ v[i] = *val;
+ }
+}
+
+
+void dijkstra(unsigned int N, unsigned int K, unsigned int *r_slap, unsigned int *J_slap,
+ double *W_slap, int s, double *dist, int *prev){
+
+ int i, cur_node, n;
+ double dist_cur_node, dist_neigh_node, w;
+
+ gen_pqueue_t *qdist;
+ node_w_t *elem;
+
+
+ init_prio_queue(&qdist, N);
+
+ for (i=0; i<N; i++){
+ elem = malloc(sizeof(node_w_t));
+ elem->i = i;
+ if (i != s)
+ elem->w = INFINITY;
+ else
+ elem->w = 0.0;
+ gen_pqueue_insert(qdist, elem);
+ prev[i] = -1;
+ dist[i] = INFINITY;
+ }
+
+
+ while (!gen_pqueue_delete(qdist, (void**)&elem)){ /* get the node with minimum distance */
+ cur_node = qdist->funs.get_id(elem);
+ dist_cur_node = *((double*) qdist->funs.get_key(elem));
+ if (dist_cur_node == INFINITY){ /* No more nodes are reachable from the origin */
+ free(elem);
+ gen_pqueue_destroy(qdist);
+ return;
+ }
+ dist[cur_node] = dist_cur_node;
+ for(i=r_slap[cur_node]; i<r_slap[cur_node + 1]; i++){
+ n = J_slap[i];
+ w = W_slap[i];
+
+ dist_neigh_node = dist_cur_node + w;
+ if (dist[n] >= dist_neigh_node){
+ /* now we call gen_pqueue_change_key, which updates the key of node n */
+ gen_pqueue_change_key(qdist, gen_pqueue_get_handle(qdist, n), &dist_neigh_node);
+ prev[n] = cur_node;
+ }
+ }
+ free(elem);
+ }
+ gen_pqueue_destroy(qdist);
+}
+
+
+void dump_dists(double *v, unsigned int N){
+
+ int i;
+
+ for(i=0; i<N-1; i++){
+ if (v[i] == INFINITY){
+ printf("inf ");
+ }
+ else{
+ printf("%g ", v[i]);
+ }
+ }
+ if (v[N-1] == INFINITY){
+ printf("inf\n");
+ }
+ else{
+ printf("%g\n", v[N-1]);
+ }
+}
+
+int main(int argc, char *argv[]){
+
+
+ double *dists;
+ int *prev;
+ unsigned int N, K, s;
+ unsigned int *r_slap = NULL, *J_slap=NULL;
+ double *W_slap = NULL;
+ FILE *filein;
+
+
+ if (argc < 3){
+ usage(argv);
+ exit(1);
+ }
+
+ if (!strcmp(argv[1], "-")){
+ /* take the input from STDIN */
+ filein = stdin;
+ }
+ else {
+ filein = openfile_or_exit(argv[1], "r", 2);
+ }
+
+ read_slap_w(filein, &K, &N, &J_slap, &r_slap, &W_slap);
+
+ fclose(filein);
+
+ s = atoi(argv[2]);
+ if (s >= N){
+ fprintf(stderr, "Error!!! Source node index should be in the range [0:%d]\n",
+ N-1);
+ exit(3);
+ }
+
+ dists = malloc(N * sizeof(double));
+ prev = malloc(N * sizeof(int));
+
+ dijkstra(N, K, r_slap, J_slap, W_slap, s, dists, prev);
+ dump_dists(dists, N);
+ free(J_slap);
+ free(r_slap);
+ free(W_slap);
+ free(dists);
+ free(prev);
+}