50 lines
1003 B
C
50 lines
1003 B
C
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#include <stdlib.h>
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#include <search.h>
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#include "tsearch.h"
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void *tdelete(const void *restrict key, void **restrict rootp,
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int(*cmp)(const void *, const void *))
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{
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if (!rootp)
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return 0;
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void **a[MAXH+1];
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struct node *n = *rootp;
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struct node *parent;
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struct node *child;
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int i=0;
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/* *a[0] is an arbitrary non-null pointer that is returned when
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the root node is deleted. */
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a[i++] = rootp;
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a[i++] = rootp;
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for (;;) {
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if (!n)
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return 0;
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int c = cmp(key, n->key);
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if (!c)
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break;
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a[i++] = &n->a[c>0];
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n = n->a[c>0];
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}
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parent = *a[i-2];
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if (n->a[0]) {
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/* free the preceding node instead of the deleted one. */
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struct node *deleted = n;
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a[i++] = &n->a[0];
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n = n->a[0];
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while (n->a[1]) {
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a[i++] = &n->a[1];
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n = n->a[1];
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}
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deleted->key = n->key;
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child = n->a[0];
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} else {
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child = n->a[1];
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}
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/* freed node has at most one child, move it up and rebalance. */
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free(n);
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*a[--i] = child;
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while (--i && __tsearch_balance(a[i]));
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return parent;
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}
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