571 lines
11 KiB
C
571 lines
11 KiB
C
/* tree - balanced binary tree library
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*
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* vix 05apr94 [removed vixie.h dependencies; cleaned up formatting, names]
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* vix 22jan93 [revisited; uses RCS, ANSI, POSIX; has bug fixes]
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* vix 23jun86 [added delete uar to add for replaced nodes]
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* vix 20jun86 [added tree_delete per wirth a+ds (mod2 v.) p. 224]
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* vix 06feb86 [added tree_mung()]
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* vix 02feb86 [added tree balancing from wirth "a+ds=p" p. 220-221]
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* vix 14dec85 [written]
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*/
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/* This program text was created by Paul Vixie using examples from the book:
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* "Algorithms & Data Structures," Niklaus Wirth, Prentice-Hall, 1986, ISBN
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* 0-13-022005-1. Any errors in the conversion from Modula-2 to C are Paul
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* Vixie's.
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*
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* This code and associated documentation is hereby placed in the public
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* domain, with the wish that my name and Prof. Wirth's not be removed
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* from the source or documentation.
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*/
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#ifndef LINT
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static char RCSid[] = "$Id:";
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#endif
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/*#define DEBUG "tree"*/
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#include <stdio.h>
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#ifndef _PATH_XFER
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# include <stdlib.h>
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#else
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# include "portability.h"
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#endif
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#include "tree.h"
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#ifdef DEBUG
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static int debugDepth = 0;
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static char *debugFuncs[256];
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# define ENTER(proc) { \
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debugFuncs[debugDepth] = proc; \
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fprintf(stderr, "ENTER(%d:%s.%s)\n", \
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debugDepth, DEBUG, \
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debugFuncs[debugDepth]); \
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debugDepth++; \
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}
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# define RET(value) { \
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debugDepth--; \
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fprintf(stderr, "RET(%d:%s.%s)\n", \
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debugDepth, DEBUG, \
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debugFuncs[debugDepth]); \
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return (value); \
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}
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# define RETV { \
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debugDepth--; \
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fprintf(stderr, "RETV(%d:%s.%s)\n", \
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debugDepth, DEBUG, \
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debugFuncs[debugDepth]); \
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return; \
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}
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# define MSG(msg) fprintf(stderr, "MSG(%s)\n", msg);
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#else
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# define ENTER(proc) ;
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# define RET(value) return (value);
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# define RETV return;
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# define MSG(msg) ;
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#endif
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#ifndef TRUE
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# define TRUE 1
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# define FALSE 0
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#endif
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static tree * sprout __P( (tree **, tree_t, int *, int (*)(), void (*)()) );
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static int delete __P( (tree **, int (*)(), tree_t, void (*)(),
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int *, int *) );
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static void del __P( (tree **, int *, tree **, void (*)(), int *) );
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static void bal_L __P( (tree **, int *) );
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static void bal_R __P( (tree **, int *) );
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void
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tree_init(ppr_tree)
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tree **ppr_tree;
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{
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ENTER("tree_init")
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*ppr_tree = NULL;
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RETV
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}
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tree_t
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tree_srch(ppr_tree, pfi_compare, p_user)
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tree **ppr_tree;
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int (*pfi_compare)();
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tree_t p_user;
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{
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register int i_comp;
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ENTER("tree_srch")
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if (*ppr_tree) {
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i_comp = (*pfi_compare)(p_user, (**ppr_tree).data);
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if (i_comp > 0)
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RET(tree_srch(&(**ppr_tree).right,
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pfi_compare,
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p_user))
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if (i_comp < 0)
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RET(tree_srch(&(**ppr_tree).left,
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pfi_compare,
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p_user))
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/* not higher, not lower... this must be the one.
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*/
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RET((**ppr_tree).data)
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}
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/* grounded. NOT found.
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*/
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RET(NULL)
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}
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tree_t
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tree_add(ppr_tree, pfi_compare, p_user, pfv_uar)
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tree **ppr_tree;
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int (*pfi_compare)();
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tree_t p_user;
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void (*pfv_uar)();
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{
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int i_balance = FALSE;
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ENTER("tree_add")
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if (!sprout(ppr_tree, p_user, &i_balance, pfi_compare, pfv_uar))
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RET(NULL)
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RET(p_user)
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}
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int
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tree_delete(ppr_p, pfi_compare, p_user, pfv_uar)
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tree **ppr_p;
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int (*pfi_compare)();
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tree_t p_user;
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void (*pfv_uar)();
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{
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int i_balance = FALSE,
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i_uar_called = FALSE;
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ENTER("tree_delete");
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RET(delete(ppr_p, pfi_compare, p_user, pfv_uar,
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&i_balance, &i_uar_called))
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}
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int
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tree_trav(ppr_tree, pfi_uar)
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tree **ppr_tree;
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int (*pfi_uar)();
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{
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ENTER("tree_trav")
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if (!*ppr_tree)
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RET(TRUE)
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if (!tree_trav(&(**ppr_tree).left, pfi_uar))
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RET(FALSE)
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if (!(*pfi_uar)((**ppr_tree).data))
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RET(FALSE)
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if (!tree_trav(&(**ppr_tree).right, pfi_uar))
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RET(FALSE)
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RET(TRUE)
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}
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void
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tree_mung(ppr_tree, pfv_uar)
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tree **ppr_tree;
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void (*pfv_uar)();
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{
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ENTER("tree_mung")
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if (*ppr_tree) {
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tree_mung(&(**ppr_tree).left, pfv_uar);
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tree_mung(&(**ppr_tree).right, pfv_uar);
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if (pfv_uar)
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(*pfv_uar)((**ppr_tree).data);
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free(*ppr_tree);
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*ppr_tree = NULL;
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}
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RETV
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}
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static tree *
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sprout(ppr, p_data, pi_balance, pfi_compare, pfv_delete)
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tree **ppr;
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tree_t p_data;
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int *pi_balance;
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int (*pfi_compare)();
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void (*pfv_delete)();
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{
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tree *p1, *p2, *sub;
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int cmp;
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ENTER("sprout")
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/* are we grounded? if so, add the node "here" and set the rebalance
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* flag, then exit.
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*/
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if (!*ppr) {
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MSG("grounded. adding new node, setting h=true")
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*ppr = (tree *) malloc(sizeof(tree));
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if (*ppr) {
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(*ppr)->left = NULL;
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(*ppr)->right = NULL;
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(*ppr)->bal = 0;
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(*ppr)->data = p_data;
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*pi_balance = TRUE;
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}
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RET(*ppr);
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}
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/* compare the data using routine passed by caller.
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*/
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cmp = (*pfi_compare)(p_data, (*ppr)->data);
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/* if LESS, prepare to move to the left.
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*/
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if (cmp < 0) {
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MSG("LESS. sprouting left.")
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sub = sprout(&(*ppr)->left, p_data, pi_balance,
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pfi_compare, pfv_delete);
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if (sub && *pi_balance) { /* left branch has grown */
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MSG("LESS: left branch has grown")
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switch ((*ppr)->bal) {
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case 1: /* right branch WAS longer; bal is ok now */
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MSG("LESS: case 1.. bal restored implicitly")
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(*ppr)->bal = 0;
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*pi_balance = FALSE;
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break;
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case 0: /* balance WAS okay; now left branch longer */
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MSG("LESS: case 0.. balnce bad but still ok")
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(*ppr)->bal = -1;
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break;
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case -1: /* left branch was already too long. rebal */
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MSG("LESS: case -1: rebalancing")
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p1 = (*ppr)->left;
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if (p1->bal == -1) { /* LL */
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MSG("LESS: single LL")
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(*ppr)->left = p1->right;
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p1->right = *ppr;
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(*ppr)->bal = 0;
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*ppr = p1;
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} else { /* double LR */
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MSG("LESS: double LR")
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p2 = p1->right;
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p1->right = p2->left;
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p2->left = p1;
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(*ppr)->left = p2->right;
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p2->right = *ppr;
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if (p2->bal == -1)
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(*ppr)->bal = 1;
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else
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(*ppr)->bal = 0;
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if (p2->bal == 1)
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p1->bal = -1;
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else
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p1->bal = 0;
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*ppr = p2;
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} /*else*/
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(*ppr)->bal = 0;
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*pi_balance = FALSE;
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} /*switch*/
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} /*if*/
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RET(sub)
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} /*if*/
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/* if MORE, prepare to move to the right.
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*/
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if (cmp > 0) {
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MSG("MORE: sprouting to the right")
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sub = sprout(&(*ppr)->right, p_data, pi_balance,
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pfi_compare, pfv_delete);
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if (sub && *pi_balance) {
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MSG("MORE: right branch has grown")
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switch ((*ppr)->bal) {
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case -1:
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MSG("MORE: balance was off, fixed implicitly")
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(*ppr)->bal = 0;
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*pi_balance = FALSE;
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break;
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case 0:
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MSG("MORE: balance was okay, now off but ok")
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(*ppr)->bal = 1;
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break;
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case 1:
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MSG("MORE: balance was off, need to rebalance")
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p1 = (*ppr)->right;
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if (p1->bal == 1) { /* RR */
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MSG("MORE: single RR")
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(*ppr)->right = p1->left;
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p1->left = *ppr;
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(*ppr)->bal = 0;
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*ppr = p1;
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} else { /* double RL */
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MSG("MORE: double RL")
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p2 = p1->left;
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p1->left = p2->right;
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p2->right = p1;
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(*ppr)->right = p2->left;
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p2->left = *ppr;
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if (p2->bal == 1)
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(*ppr)->bal = -1;
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else
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(*ppr)->bal = 0;
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if (p2->bal == -1)
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p1->bal = 1;
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else
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p1->bal = 0;
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*ppr = p2;
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} /*else*/
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(*ppr)->bal = 0;
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*pi_balance = FALSE;
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} /*switch*/
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} /*if*/
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RET(sub)
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} /*if*/
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/* not less, not more: this is the same key! replace...
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*/
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MSG("FOUND: Replacing data value")
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*pi_balance = FALSE;
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if (pfv_delete)
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(*pfv_delete)((*ppr)->data);
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(*ppr)->data = p_data;
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RET(*ppr)
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}
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static int
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delete(ppr_p, pfi_compare, p_user, pfv_uar, pi_balance, pi_uar_called)
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tree **ppr_p;
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int (*pfi_compare)();
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tree_t p_user;
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void (*pfv_uar)();
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int *pi_balance;
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int *pi_uar_called;
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{
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tree *pr_q;
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int i_comp, i_ret;
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ENTER("delete")
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if (*ppr_p == NULL) {
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MSG("key not in tree")
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RET(FALSE)
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}
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i_comp = (*pfi_compare)((*ppr_p)->data, p_user);
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if (i_comp > 0) {
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MSG("too high - scan left")
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i_ret = delete(&(*ppr_p)->left, pfi_compare, p_user, pfv_uar,
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pi_balance, pi_uar_called);
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if (*pi_balance)
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bal_L(ppr_p, pi_balance);
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} else if (i_comp < 0) {
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MSG("too low - scan right")
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i_ret = delete(&(*ppr_p)->right, pfi_compare, p_user, pfv_uar,
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pi_balance, pi_uar_called);
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if (*pi_balance)
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bal_R(ppr_p, pi_balance);
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} else {
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MSG("equal")
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pr_q = *ppr_p;
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if (pr_q->right == NULL) {
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MSG("right subtree null")
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*ppr_p = pr_q->left;
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*pi_balance = TRUE;
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} else if (pr_q->left == NULL) {
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MSG("right subtree non-null, left subtree null")
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*ppr_p = pr_q->right;
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*pi_balance = TRUE;
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} else {
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MSG("neither subtree null")
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del(&pr_q->left, pi_balance, &pr_q,
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pfv_uar, pi_uar_called);
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if (*pi_balance)
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bal_L(ppr_p, pi_balance);
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}
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if (!*pi_uar_called && pfv_uar)
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(*pfv_uar)(pr_q->data);
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free(pr_q); /* thanks to wuth@castrov.cuc.ab.ca */
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i_ret = TRUE;
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}
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RET(i_ret)
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}
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static void
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del(ppr_r, pi_balance, ppr_q, pfv_uar, pi_uar_called)
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tree **ppr_r;
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int *pi_balance;
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tree **ppr_q;
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void (*pfv_uar)();
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int *pi_uar_called;
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{
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ENTER("del")
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if ((*ppr_r)->right != NULL) {
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del(&(*ppr_r)->right, pi_balance, ppr_q,
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pfv_uar, pi_uar_called);
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if (*pi_balance)
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bal_R(ppr_r, pi_balance);
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} else {
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if (pfv_uar)
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(*pfv_uar)((*ppr_q)->data);
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*pi_uar_called = TRUE;
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(*ppr_q)->data = (*ppr_r)->data;
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*ppr_q = *ppr_r;
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*ppr_r = (*ppr_r)->left;
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*pi_balance = TRUE;
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}
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RETV
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}
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static void
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bal_L(ppr_p, pi_balance)
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tree **ppr_p;
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int *pi_balance;
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{
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tree *p1, *p2;
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int b1, b2;
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ENTER("bal_L")
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MSG("left branch has shrunk")
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switch ((*ppr_p)->bal) {
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case -1:
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MSG("was imbalanced, fixed implicitly")
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(*ppr_p)->bal = 0;
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break;
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case 0:
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MSG("was okay, is now one off")
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(*ppr_p)->bal = 1;
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*pi_balance = FALSE;
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break;
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case 1:
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MSG("was already off, this is too much")
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p1 = (*ppr_p)->right;
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b1 = p1->bal;
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if (b1 >= 0) {
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MSG("single RR")
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(*ppr_p)->right = p1->left;
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p1->left = *ppr_p;
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if (b1 == 0) {
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MSG("b1 == 0")
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(*ppr_p)->bal = 1;
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p1->bal = -1;
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*pi_balance = FALSE;
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} else {
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MSG("b1 != 0")
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(*ppr_p)->bal = 0;
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p1->bal = 0;
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}
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*ppr_p = p1;
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} else {
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MSG("double RL")
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p2 = p1->left;
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b2 = p2->bal;
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p1->left = p2->right;
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p2->right = p1;
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(*ppr_p)->right = p2->left;
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p2->left = *ppr_p;
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if (b2 == 1)
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(*ppr_p)->bal = -1;
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else
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(*ppr_p)->bal = 0;
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if (b2 == -1)
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p1->bal = 1;
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else
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p1->bal = 0;
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*ppr_p = p2;
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p2->bal = 0;
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}
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}
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RETV
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}
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static void
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bal_R(ppr_p, pi_balance)
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tree **ppr_p;
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int *pi_balance;
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{
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tree *p1, *p2;
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int b1, b2;
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ENTER("bal_R")
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MSG("right branch has shrunk")
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switch ((*ppr_p)->bal) {
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case 1:
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MSG("was imbalanced, fixed implicitly")
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(*ppr_p)->bal = 0;
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break;
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case 0:
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MSG("was okay, is now one off")
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(*ppr_p)->bal = -1;
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*pi_balance = FALSE;
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break;
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case -1:
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MSG("was already off, this is too much")
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p1 = (*ppr_p)->left;
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b1 = p1->bal;
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if (b1 <= 0) {
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MSG("single LL")
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(*ppr_p)->left = p1->right;
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p1->right = *ppr_p;
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if (b1 == 0) {
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MSG("b1 == 0")
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(*ppr_p)->bal = -1;
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p1->bal = 1;
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*pi_balance = FALSE;
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} else {
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MSG("b1 != 0")
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(*ppr_p)->bal = 0;
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p1->bal = 0;
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}
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*ppr_p = p1;
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} else {
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MSG("double LR")
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p2 = p1->right;
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b2 = p2->bal;
|
|
p1->right = p2->left;
|
|
p2->left = p1;
|
|
(*ppr_p)->left = p2->right;
|
|
p2->right = *ppr_p;
|
|
if (b2 == -1)
|
|
(*ppr_p)->bal = 1;
|
|
else
|
|
(*ppr_p)->bal = 0;
|
|
if (b2 == 1)
|
|
p1->bal = -1;
|
|
else
|
|
p1->bal = 0;
|
|
*ppr_p = p2;
|
|
p2->bal = 0;
|
|
}
|
|
}
|
|
RETV
|
|
}
|