From feb8ebaeb76fa1c94de2dd7c4e5a0999b313f8c6 Mon Sep 17 00:00:00 2001 From: David Monniaux Date: Thu, 6 Jun 2019 20:09:32 +0200 Subject: GLPK 4.65 --- test/monniaux/glpk-4.65/src/api/topsort.c | 123 ++++++++++++++++++++++++++++++ 1 file changed, 123 insertions(+) create mode 100644 test/monniaux/glpk-4.65/src/api/topsort.c (limited to 'test/monniaux/glpk-4.65/src/api/topsort.c') diff --git a/test/monniaux/glpk-4.65/src/api/topsort.c b/test/monniaux/glpk-4.65/src/api/topsort.c new file mode 100644 index 00000000..971937f2 --- /dev/null +++ b/test/monniaux/glpk-4.65/src/api/topsort.c @@ -0,0 +1,123 @@ +/* topsort.c (topological sorting of acyclic digraph) */ + +/*********************************************************************** +* This code is part of GLPK (GNU Linear Programming Kit). +* +* Copyright (C) 2010-2016 Andrew Makhorin, Department for Applied +* Informatics, Moscow Aviation Institute, Moscow, Russia. All rights +* reserved. E-mail: . +* +* GLPK 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. +* +* GLPK 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 GLPK. If not, see . +***********************************************************************/ + +#include "env.h" +#include "glpk.h" + +/*********************************************************************** +* NAME +* +* glp_top_sort - topological sorting of acyclic digraph +* +* SYNOPSIS +* +* int glp_top_sort(glp_graph *G, int v_num); +* +* DESCRIPTION +* +* The routine glp_top_sort performs topological sorting of vertices of +* the specified acyclic digraph. +* +* The parameter v_num specifies an offset of the field of type int in +* the vertex data block, to which the routine stores the vertex number +* assigned. If v_num < 0, vertex numbers are not stored. +* +* The vertices are numbered from 1 to n, where n is the total number +* of vertices in the graph. The vertex numbering has the property that +* for every arc (i->j) in the graph the condition num(i) < num(j) +* holds. Special case num(i) = 0 means that vertex i is not assigned a +* number, because the graph is *not* acyclic. +* +* RETURNS +* +* If the graph is acyclic and therefore all the vertices have been +* assigned numbers, the routine glp_top_sort returns zero. Otherwise, +* if the graph is not acyclic, the routine returns the number of +* vertices which have not been numbered, i.e. for which num(i) = 0. */ + +static int top_sort(glp_graph *G, int num[]) +{ glp_arc *a; + int i, j, cnt, top, *stack, *indeg; + /* allocate working arrays */ + indeg = xcalloc(1+G->nv, sizeof(int)); + stack = xcalloc(1+G->nv, sizeof(int)); + /* determine initial indegree of each vertex; push into the stack + the vertices having zero indegree */ + top = 0; + for (i = 1; i <= G->nv; i++) + { num[i] = indeg[i] = 0; + for (a = G->v[i]->in; a != NULL; a = a->h_next) + indeg[i]++; + if (indeg[i] == 0) + stack[++top] = i; + } + /* assign numbers to vertices in the sorted order */ + cnt = 0; + while (top > 0) + { /* pull vertex i from the stack */ + i = stack[top--]; + /* it has zero indegree in the current graph */ + xassert(indeg[i] == 0); + /* so assign it a next number */ + xassert(num[i] == 0); + num[i] = ++cnt; + /* remove vertex i from the current graph, update indegree of + its adjacent vertices, and push into the stack new vertices + whose indegree becomes zero */ + for (a = G->v[i]->out; a != NULL; a = a->t_next) + { j = a->head->i; + /* there exists arc (i->j) in the graph */ + xassert(indeg[j] > 0); + indeg[j]--; + if (indeg[j] == 0) + stack[++top] = j; + } + } + /* free working arrays */ + xfree(indeg); + xfree(stack); + return G->nv - cnt; +} + +int glp_top_sort(glp_graph *G, int v_num) +{ glp_vertex *v; + int i, cnt, *num; + if (v_num >= 0 && v_num > G->v_size - (int)sizeof(int)) + xerror("glp_top_sort: v_num = %d; invalid offset\n", v_num); + if (G->nv == 0) + { cnt = 0; + goto done; + } + num = xcalloc(1+G->nv, sizeof(int)); + cnt = top_sort(G, num); + if (v_num >= 0) + { for (i = 1; i <= G->nv; i++) + { v = G->v[i]; + memcpy((char *)v->data + v_num, &num[i], sizeof(int)); + } + } + xfree(num); +done: return cnt; +} + +/* eof */ -- cgit