From 3aee2fd43e3059a699af2b63c6f2395e5a55e515 Mon Sep 17 00:00:00 2001
From: KatolaZ <katolaz@freaknet.org>
Date: Wed, 27 Sep 2017 15:06:31 +0100
Subject: First commit on github -- NetBunch 1.0

---
 src/components/components.c | 207 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 207 insertions(+)
 create mode 100644 src/components/components.c

(limited to 'src/components/components.c')

diff --git a/src/components/components.c b/src/components/components.c
new file mode 100644
index 0000000..a5dc52d
--- /dev/null
+++ b/src/components/components.c
@@ -0,0 +1,207 @@
+/**
+ *  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 Depth-First Search algorithm to find
+ *  the connected components of a graph provided as input.
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "utils.h"
+
+
+
+void usage(char *argv[]){
+  printf("********************************************************************\n"
+         "**                                                                **\n"
+         "**                      -*-  components  -*-                      **\n"
+         "**                                                                **\n"
+         "**   Find the connected components of an undirected graph         **\n"
+         "**   and print on output their size and/or the list of nodes      **\n"
+         "**   belonging to each component. The first parameter 'graph_in'  **\n"
+         "**   is the name of the file containing the edge list of the      **\n"
+         "**   graph.                                                       **\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 the SIZE of each connected      **\n"
+         "**   component of the graph, one per line:                        **\n"
+         "**                                                                **\n"
+         "**      size_1                                                    **\n"
+         "**      size_2                                                    **\n"
+         "**      size_3                                                    **\n"
+         "**                                                                **\n"
+         "**    The sizes are in no particular order.                       **\n"
+         "**                                                                **\n"
+         "**    If 'SHOW' is given as second argument, the list of nodes    **\n"
+         "**    belonging to each component is printed as well, in the      **\n"
+         "**    format:                                                     **\n"
+         "**                                                                **\n"
+         "**      size_1: node_1 node_2 node_3 ....                         **\n"
+         "**      size_2: node_1 node_2 node_3 ....                         **\n"
+         "**      size_3: node_1 node_2 node_3 ....                         **\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> [SHOW]\n\n" , argv[0]);
+}
+
+
+
+/**
+ *
+ * Depth-First search on node i....
+ *
+ */
+int dfs(unsigned int i, unsigned int *J_slap, unsigned int *r_slap, 
+        unsigned int N, unsigned int nc, 
+        unsigned int *ic, unsigned int *f, 
+        char reset){
+  
+  static unsigned int time;
+  unsigned int j, s;
+  
+  if(reset){
+    time = 0;
+  }
+  
+  ic[i] = nc;
+  s = 1;
+  time += 1;
+  
+  for(j=r_slap[i]; j<r_slap[i+1]; j++){
+    if (ic[J_slap[j]] == 0){
+      s += dfs(J_slap[j], J_slap, r_slap, N, nc, ic, f, 0);
+    }
+  }
+  time += 1;
+  f[i] = time;
+  return s;
+}
+
+/**
+ * 
+ * Find all the components of the given graph, using the Depth-First
+ * Search algorithm
+ *
+ */
+
+int components(unsigned int *J_slap, unsigned int *r_slap,
+                unsigned int N, unsigned int **ic, 
+                unsigned int **f, unsigned int **sizes){
+
+  unsigned int nc, s;
+  unsigned int i;
+
+  *ic = malloc(N * sizeof(unsigned int));
+  *f = malloc(N * sizeof(unsigned int));
+  *sizes = malloc((N+1) * sizeof(unsigned int));
+  
+  for(i=0; i<N; i++){
+    (*ic)[i] = 0;
+    (*f)[i] = 0;
+  }
+  nc = 0;
+  for(i=0; i<N; i++){
+    while( i<N && (*ic) [i] != 0 )
+      i += 1;
+    if (i == N)
+      break;
+    nc += 1;
+    s = dfs(i, J_slap, r_slap, N, nc, *ic, *f, 1);
+    (*sizes)[nc] = s;
+  }
+  return nc;
+}
+
+
+int main(int argc, char *argv[]){
+
+
+  FILE *filein;
+  unsigned int N, K;
+  unsigned int *J_slap, *r_slap;
+  unsigned int *ic, *f, *sizes;
+  unsigned int nc, i, j;
+  char show = 0;
+
+
+  if (argc < 2){
+    usage(argv);
+    exit(1);
+  }
+  if (argc >2 && !my_strcasecmp("SHOW", argv[2])){
+    show = 1;
+  }  
+
+  if (!strcmp(argv[1], "-")){
+    /* take the input from STDIN */
+    filein = stdin;
+  }
+  else {
+    filein = openfile_or_exit(argv[1], "r", 2);
+  }
+
+  read_slap(filein, &K, &N, &J_slap, &r_slap);
+  fclose(filein);
+  
+  nc = components(J_slap, r_slap, N, &ic, &f, &sizes);  
+  for(i=1; i<=nc; i++){
+    printf("%d", sizes[i]);
+    if (show){
+      printf(":");
+        for(j=0; j<N; j++){
+          if (ic[j] == i){
+            printf(" %d", j);
+          }
+        }
+      printf("\n");
+    }
+    else{
+      printf("\n");
+    }
+  }
+  free(f);
+  free(ic);
+  free(sizes);
+  free(J_slap);
+  free(r_slap);
+}
-- 
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