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/largest_component.c | 191 +++++++++++++++++++++++++++++++++++++
 1 file changed, 191 insertions(+)
 create mode 100644 src/components/largest_component.c

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

diff --git a/src/components/largest_component.c b/src/components/largest_component.c
new file mode 100644
index 0000000..06a26eb
--- /dev/null
+++ b/src/components/largest_component.c
@@ -0,0 +1,191 @@
+/**
+ *  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
+ *
+ ***********************************************************************
+ *
+ *  Compute the largest connected component of a graph (i.e., the
+ *  connected component that contains the largest number of nodes).
+ *
+ *
+ */
+
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "utils.h"
+
+
+void usage(char *argv[]){
+  printf("********************************************************************\n"
+         "**                                                                **\n"
+         "**                  -*- largest_component -*-                     **\n"
+         "**                                                                **\n"
+         "**   Find the largest connected component of 'graph_in'.          **\n"
+         "**                                                                **\n"
+         "**   The input file 'graph_in' is an edge-list:                   **\n"
+         "**                                                                **\n"
+         "**                            I_1 J_1                             **\n"
+         "**                            I_2 J_2                             **\n"
+         "**                            I_3 J_3                             **\n"
+         "**                            ... ...                             **\n"
+         "**                            I_K J_K                             **\n"
+         "**                                                                **\n"
+         "**    If 'graph_in' is equal to '-' (dash), read the file from    **\n" 
+         "**    the standard input (STDIN).                                 **\n"
+         "**                                                                **\n"
+         "**    The program prints on STDOUT the edge list of the largest   **\n"
+         "**    connected component of 'graph_in'.                          **\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 2009-2017 (v.nicosia@qmul.ac.uk)\n"
+         "********************************************************************\n\n"
+         );
+  
+  printf("Usage: %s <graph_in>\n", argv[0]);
+}
+
+
+
+/**
+ *
+ * Depth-First search on the 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
+ *
+ */
+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 * sizeof(unsigned int));
+  
+  for(i=0; i<N; i++){
+    (*ic)[i] = 0;
+    (*f)[i] = 0;
+  }
+  nc = 0;
+  for(i=0; i<N; i++){
+    while( (*ic) [i] != 0 && i < N)
+      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, max_c;
+  
+  
+  if (argc < 2){
+    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(filein, &K, &N, &J_slap, &r_slap);
+  fclose(filein);
+  nc = components(J_slap, r_slap, N, &ic, &f, &sizes);
+  
+  max_c = 1;
+  for(i=2; i<=nc; i++){
+    if (sizes[i] > sizes[max_c])
+      max_c = i;
+  }
+  for(i=0; i<N; i++){
+    if(ic[i] == max_c){
+      for(j=r_slap[i]; j<r_slap[i+1]; j++){
+        if (J_slap[j] > i)
+          fprintf(stdout, "%d %d\n", i, J_slap[j]);
+      }
+    }
+  }
+  free(J_slap); 
+  free(r_slap);
+  free(ic);
+  free(f);
+  free(sizes);
+}
-- 
cgit v1.2.3