25 lines
972 B
C
25 lines
972 B
C
#include "cs.h"
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/* post order a forest */
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int *cs_post (const int *parent, int n)
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{
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int j, k = 0, *post, *w, *head, *next, *stack ;
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if (!parent) return (NULL) ; /* check inputs */
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post = cs_malloc (n, sizeof (int)) ; /* allocate result */
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w = cs_malloc (3*n, sizeof (int)) ; /* get workspace */
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if (!w || !post) return (cs_idone (post, NULL, w, 0)) ;
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head = w ; next = w + n ; stack = w + 2*n ;
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for (j = 0 ; j < n ; j++) head [j] = -1 ; /* empty linked lists */
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for (j = n-1 ; j >= 0 ; j--) /* traverse nodes in reverse order*/
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{
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if (parent [j] == -1) continue ; /* j is a root */
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next [j] = head [parent [j]] ; /* add j to list of its parent */
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head [parent [j]] = j ;
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}
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for (j = 0 ; j < n ; j++)
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{
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if (parent [j] != -1) continue ; /* skip j if it is not a root */
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k = cs_tdfs (j, k, head, next, post, stack) ;
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}
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return (cs_idone (post, NULL, w, 1)) ; /* success; free w, return post */
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}
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