Initial revision
This commit is contained in:
davi
329
src/graph.c
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329
src/graph.c
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#include "graph.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <limits.h>
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#include <assert.h>
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#include <string.h>
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#include "vstack.h"
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//#define DEBUG
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#include "debug.h"
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#define abs_edge(e, i) (e % g->nedges + i * g->nedges)
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struct __graph_t
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{
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uint32 nnodes;
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uint32 nedges;
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uint32 *edges;
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uint32 *first;
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uint32 *next;
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uint8 *critical_nodes; /* included -- Fabiano*/
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uint32 ncritical_nodes; /* included -- Fabiano*/
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uint32 cedges;
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int shrinking;
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};
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static uint32 EMPTY = UINT_MAX;
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graph_t *graph_new(uint32 nnodes, uint32 nedges)
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{
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graph_t *graph = (graph_t *)malloc(sizeof(graph_t));
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if (!graph) return NULL;
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graph->edges = (uint32 *)malloc(sizeof(uint32) * 2 * nedges);
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graph->next = (uint32 *)malloc(sizeof(uint32) * 2 * nedges);
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graph->first = (uint32 *)malloc(sizeof(uint32) * nnodes);
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graph->critical_nodes = NULL; /* included -- Fabiano*/
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graph->ncritical_nodes = 0; /* included -- Fabiano*/
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graph->nnodes = nnodes;
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graph->nedges = nedges;
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graph_clear_edges(graph);
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return graph;
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}
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void graph_destroy(graph_t *graph)
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{
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DEBUGP("Destroying graph\n");
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free(graph->edges);
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free(graph->first);
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free(graph->next);
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free(graph->critical_nodes); /* included -- Fabiano*/
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free(graph);
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return;
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}
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void graph_print(graph_t *g)
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{
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uint32 i, e;
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for (i = 0; i < g->nnodes; ++i)
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{
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DEBUGP("Printing edges connected to %u\n", i);
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e = g->first[i];
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if (e != EMPTY)
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{
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printf("%u -> %u\n", g->edges[abs_edge(e, 0)], g->edges[abs_edge(e, 1)]);
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while ((e = g->next[e]) != EMPTY)
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{
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printf("%u -> %u\n", g->edges[abs_edge(e, 0)], g->edges[abs_edge(e, 1)]);
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}
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}
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}
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return;
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}
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void graph_add_edge(graph_t *g, uint32 v1, uint32 v2)
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{
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uint32 e = g->cedges;
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assert(v1 < g->nnodes);
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assert(v2 < g->nnodes);
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assert(e < g->nedges);
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assert(!g->shrinking);
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g->next[e] = g->first[v1];
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g->first[v1] = e;
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g->edges[e] = v2;
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g->next[e + g->nedges] = g->first[v2];
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g->first[v2] = e + g->nedges;
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g->edges[e + g->nedges] = v1;
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++(g->cedges);
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}
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static int check_edge(graph_t *g, uint32 e, uint32 v1, uint32 v2)
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{
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DEBUGP("Checking edge %u %u looking for %u %u\n", g->edges[abs_edge(e, 0)], g->edges[abs_edge(e, 1)], v1, v2);
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if (g->edges[abs_edge(e, 0)] == v1 && g->edges[abs_edge(e, 1)] == v2) return 1;
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if (g->edges[abs_edge(e, 0)] == v2 && g->edges[abs_edge(e, 1)] == v1) return 1;
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return 0;
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}
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uint32 graph_edge_id(graph_t *g, uint32 v1, uint32 v2)
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{
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uint32 e;
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e = g->first[v1];
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assert(e != EMPTY);
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if (check_edge(g, e, v1, v2)) return abs_edge(e, 0);
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do
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{
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e = g->next[e];
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assert(e != EMPTY);
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}
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while (!check_edge(g, e, v1, v2));
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return abs_edge(e, 0);
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}
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static void del_edge_point(graph_t *g, uint32 v1, uint32 v2)
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{
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uint32 e, prev;
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DEBUGP("Deleting edge point %u %u\n", v1, v2);
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e = g->first[v1];
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if (check_edge(g, e, v1, v2))
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{
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g->first[v1] = g->next[e];
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//g->edges[e] = EMPTY;
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DEBUGP("Deleted\n");
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return;
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}
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DEBUGP("Checking linked list\n");
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do
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{
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prev = e;
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e = g->next[e];
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assert(e != EMPTY);
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}
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while (!check_edge(g, e, v1, v2));
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g->next[prev] = g->next[e];
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//g->edges[e] = EMPTY;
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DEBUGP("Deleted\n");
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}
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void graph_del_edge(graph_t *g, uint32 v1, uint32 v2)
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{
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g->shrinking = 1;
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del_edge_point(g, v1, v2);
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del_edge_point(g, v2, v1);
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}
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void graph_clear_edges(graph_t *g)
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{
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uint32 i;
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for (i = 0; i < g->nnodes; ++i) g->first[i] = EMPTY;
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for (i = 0; i < g->nedges*2; ++i)
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{
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g->edges[i] = EMPTY;
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g->next[i] = EMPTY;
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}
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g->cedges = 0;
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g->shrinking = 0;
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}
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static int find_degree1_edge(graph_t *g, uint32 v, char *deleted, uint32 *e)
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{
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uint32 edge = g->first[v];
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char found = 0;
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DEBUGP("Checking degree of vertex %u\n", v);
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if (edge == EMPTY) return 0;
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else if (!deleted[abs_edge(edge, 0)])
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{
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found = 1;
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*e = edge;
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}
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while(1)
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{
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edge = g->next[edge];
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if (edge == EMPTY) break;
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if (deleted[abs_edge(edge, 0)]) continue;
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if (found) return 0;
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DEBUGP("Found first edge\n");
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*e = edge;
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found = 1;
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}
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return found;
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}
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static void cyclic_del_edge(graph_t *g, uint32 v, char *deleted)
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{
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uint32 e;
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char degree1;
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uint32 v1 = v;
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uint32 v2 = 0;
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degree1 = find_degree1_edge(g, v1, deleted, &e);
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if (!degree1) return;
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while(1)
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{
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DEBUGP("Deleting edge %u (%u->%u)\n", e, g->edges[abs_edge(e, 0)], g->edges[abs_edge(e, 1)]);
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deleted[abs_edge(e, 0)] = 1;
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v2 = g->edges[abs_edge(e, 0)];
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if (v2 == v1) v2 = g->edges[abs_edge(e, 1)];
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DEBUGP("Checking if second endpoint %u has degree 1\n", v2);
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degree1 = find_degree1_edge(g, v2, deleted, &e);
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if (degree1)
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{
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DEBUGP("Inspecting vertex %u\n", v2);
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v1 = v2;
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}
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else break;
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}
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}
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int graph_is_cyclic(graph_t *g)
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{
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uint32 i;
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uint32 v;
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char *deleted = (char *)malloc(g->nedges*sizeof(char));
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memset(deleted, 0, g->nedges);
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DEBUGP("Looking for cycles in graph with %u vertices and %u edges\n", g->nnodes, g->nedges);
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for (v = 0; v < g->nnodes; ++v)
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{
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cyclic_del_edge(g, v, deleted);
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}
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for (i = 0; i < g->nedges; ++i)
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{
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if (!(deleted[i]))
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{
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DEBUGP("Edge %u %u->%u was not deleted\n", i, g->edges[i], g->edges[i + g->nedges]);
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free(deleted);
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return 1;
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}
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}
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free(deleted);
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return 0;
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}
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uint8 graph_node_is_critical(graph_t * g, uint32 v) /* included -- Fabiano */
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{
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return g->critical_nodes[v];
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}
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void graph_obtain_critical_nodes(graph_t *g) /* included -- Fabiano*/
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{
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uint32 i;
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uint32 v;
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char *deleted = (char *)malloc(g->nedges*sizeof(char));
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memset(deleted, 0, g->nedges);
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/* g->critical_nodes = (uint8 *)malloc((size_t)(ceil(g->nnodes*sizeof(uint8)/8.))); */
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g->critical_nodes = (uint8 *)malloc(g->nnodes*sizeof(uint8));
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g->ncritical_nodes = 0;
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DEBUGP("Looking for the 2-core in graph with %u vertices and %u edges\n", g->nnodes, g->nedges);
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for (v = 0; v < g->nnodes; ++v)
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{
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cyclic_del_edge(g, v, deleted);
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}
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for (i = 0; i < g->nedges; ++i)
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{
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if (!(deleted[i]))
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{
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DEBUGP("Edge %u %u->%u belongs to the 2-core\n", i, g->edges[i], g->edges[i + g->nedges]);
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if(!(g->critical_nodes[g->edges[i]]))
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{
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g->ncritical_nodes ++;
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g->critical_nodes[g->edges[i]] = 1;
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}
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if(!(g->critical_nodes[g->edges[i + g->nedges]]))
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{
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g->ncritical_nodes ++;
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g->critical_nodes[g->edges[i + g->nedges]] = 1;
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}
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}
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}
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free(deleted);
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}
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uint8 graph_contains_edge(graph_t *g, uint32 v1, uint32 v2) /* included -- Fabiano*/
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{
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uint32 e;
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e = g->first[v1];
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if(e == EMPTY) return 0;
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if (check_edge(g, e, v1, v2)) return 1;
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do
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{
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e = g->next[e];
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if(e == EMPTY) return 0;
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}
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while (!check_edge(g, e, v1, v2));
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return 1;
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}
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uint32 graph_vertex_id(graph_t *g, uint32 e, uint32 id) /* included -- Fabiano*/
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{
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return (g->edges[e + id*g->nedges]);
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}
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uint32 graph_ncritical_nodes(graph_t *g) /* included -- Fabiano*/
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{
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return g->ncritical_nodes;
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}
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graph_iterator_t graph_neighbors_it(graph_t *g, uint32 v)
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{
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graph_iterator_t it;
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it.vertex = v;
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it.edge = g->first[v];
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return it;
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}
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uint32 graph_next_neighbor(graph_t *g, graph_iterator_t* it)
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{
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uint32 ret;
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if(it->edge == EMPTY) return GRAPH_NO_NEIGHBOR;
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if (g->edges[it->edge] == it->vertex) ret = g->edges[it->edge + g->nedges];
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else ret = g->edges[it->edge];
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it->edge = g->next[it->edge];
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return ret;
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}
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