Exclua vários nós de uma árvore de pesquisa binária
https://stackoverflow.com/questions/1920013
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20-09-2019 - |
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Eu tenho uma árvore de pesquisa binária criada em C. O problema é que não consigo encontrar uma maneira eficiente de excluir todos os nós com EG, ID> 5.
Quando percorre a árvore, se eu excluir um nó, a recursão está recebendo erro, porque a estrutura não é a mesma.
Existe alguma maneira, em vez de usar uma pilha de ajuda para manter os dados antes de excluí -los da árvore?
Solução
Você tentou o Postorder?
Exclua o nó após seus filhos.
Outras dicas
Kostas. Você precisa fornecer mais informações.
Uma árvore binária significa apenas uma árvore cujos nós têm (no máximo) dois filhos. Os dados podem ser encomendados de várias maneiras em uma árvore assim:
- Não ordenado: não há relação entre um pai e seus nós.
- Heap: um nó é maior que (ou menor que) todos os seus filhos
- Pedido: Uma criança é designada menor e o outro maior. Todos os valores menores que a raiz são de um lado, todos os valores maiores para o outro.
Se você nos der um código, podemos ajudar mais.
Vou preferir a árvore AVL para esta satinação.
Aqui está o código, pegue o que você deseja
class BSTree
{
/* */ public static final int INSERT = 1;
/* */ public static final int DELETE = -1;
/* */ BTNode root;
/* */ boolean AVL;
/* */ boolean SPL;
/* */ boolean RBL;
/* */ BTNode lastnode;
/* */ int nextside;
/* */
/* */ public BSTree(int mode)
/* */ {
/* 18 */ this.root = null;
/* 19 */ setMode(mode, true);
/* */ }
/* */
/* */ public void setMode(int mode, boolean state) {
/* 23 */ switch (mode)
/* */ {
/* */ case 1:
/* 26 */ if (state == true)
/* */ {
/* 28 */ this.AVL = true;
/* 29 */ this.SPL = false;
/* 30 */ this.RBL = false;
/* */
/* 26 */ return;
/* */ }
/* */
/* 33 */ this.AVL = false;
/* 34 */ break;
/* */ case 2:
/* 37 */ if (state == true)
/* */ {
/* 39 */ this.SPL = true;
/* 40 */ this.AVL = false;
/* 41 */ this.RBL = false;
/* */
/* 37 */ return;
/* */ }
/* */
/* 44 */ this.SPL = false;
/* 45 */ break;
/* */ case 3:
/* 48 */ if (state == true)
/* */ {
/* 50 */ this.RBL = true;
/* 51 */ this.AVL = false;
/* 52 */ this.SPL = false;
/* */
/* 48 */ return;
/* */ }
/* */
/* 55 */ this.RBL = false;
/* 56 */ break;
/* */ default:
/* 59 */ this.AVL = false;
/* 60 */ this.SPL = false;
/* 61 */ this.RBL = false;
/* */ }
/* */ }
/* */
/* */ public boolean isAVL() {
/* 66 */ return this.AVL;
/* */ }
/* */
/* */ public boolean isSPL() {
/* 70 */ return this.SPL;
/* */ }
/* */
/* */ public boolean isRBL() {
/* 74 */ return this.RBL;
/* */ }
/* */
/* */ public BTNode getRoot()
/* */ {
/* 79 */ return this.root;
/* */ }
/* */
/* */ public void setRoot(BTNode node) {
/* 83 */ this.root = node;
/* */ }
/* */
/* */ public boolean isEmpty() {
/* 87 */ return (this.root == null);
/* */ }
/* */
/* */ public int getDepth()
/* */ {
/* 92 */ int maxdepth = 0;
/* 93 */ for (BTNode node = this.root; node != null; node = node.nextPrO())
/* */ {
/* 95 */ int depth = node.getDepth(this.root);
/* 96 */ if (depth > maxdepth)
/* 97 */ maxdepth = depth;
/* */ }
/* 99 */ return maxdepth;
/* */ }
/* */
/* */ public void destroy(BTNode node)
/* */ {
/* 104 */ node = null;
/* */ }
/* */
/* */ public BTNode find(BTData data)
/* */ {
/* 113 */ BTNode node = locate(data);
/* 114 */ if (isSPL())
/* 115 */ splay(this.lastnode);
/* 116 */ return node;
/* */ }
/* */
/* */ public BTNode insert(BTData data) {
/* 120 */ if (isSPL()) {
/* 121 */ return insertSPL(data);
/* */ }
/* 123 */ if (isAVL()) {
/* 124 */ return insertAVL(data);
/* */ }
/* 126 */ if (isRBL()) {
/* 127 */ return insertRBL(data);
/* */ }
/* 129 */ return insertBST(data);
/* */ }
/* */
/* */ public BTNode delete(BTData data, int minmax) {
/* 133 */ if (isAVL()) {
/* 134 */ return deleteAVL(data, minmax);
/* */ }
/* 136 */ if (isSPL()) {
/* 137 */ return deleteSPL(data, minmax);
/* */ }
/* 139 */ if (isRBL()) {
/* 140 */ return deleteRBL(data, minmax);
/* */ }
/* 142 */ return deleteBST(data, minmax);
/* */ }
/* */
/* */ public BTNode locate(BTData data)
/* */ {
/* 150 */ BTNode node = this.root;
/* 151 */ BTNode next = null;
/* 152 */ int side = 0;
/* */
/* 154 */ while (node != null)
/* */ {
/* 156 */ side = node.compareSide(data);
/* 157 */ next = node.getChild(side);
/* 158 */ if (next == node) break; if (next == null)
/* */ break;
/* 160 */ node = next;
/* */ }
/* 162 */ this.lastnode = node;
/* 163 */ this.nextside = side;
/* 164 */ return next;
/* */ }
/* */
/* */ public BTNode add(BTNode node, int side, BTData data)
/* */ {
/* 170 */ BTNode newnode = new BTNode(data);
/* 171 */ link(node, side, newnode);
/* 172 */ return newnode;
/* */ }
/* */
/* */ public BTNode remove(BTNode node)
/* */ {
/* 181 */ BTNode child = node.getChild();
/* 182 */ BTNode parent = node.getParent();
/* 183 */ int side = node.getSide();
/* 184 */ link(parent, side, child);
/* 185 */ destroy(node);
/* 186 */ return parent;
/* */ }
/* */
/* */ public void link(BTNode parent, int side, BTNode child)
/* */ {
/* 193 */ if (child != null)
/* 194 */ child.setParent(parent);
/* 195 */ if (parent != null)
/* 196 */ parent.setChild(side, child);
/* */ else
/* 198 */ this.root = child;
/* */ }
/* */
/* */ public BTNode rotate(BTNode node, int side)
/* */ {
/* 206 */ BTNode parent = node.getParent();
/* 207 */ BTNode child = node.getChild(-side);
/* 208 */ BTNode grand = child.getChild(side);
/* */
/* 210 */ link(node, -side, grand);
/* 211 */ link(parent, node.getSide(), child);
/* 212 */ link(child, side, node);
/* 213 */ return child;
/* */ }
/* */
/* */ public BTNode swap(BTNode node, int minmax)
/* */ {
/* 222 */ BTNode swap = getSuccessor(node, minmax);
/* 223 */ BTNode temp = node;
/* 224 */ swapData(node, swap);
/* 225 */ node = swap;
/* 226 */ swap = temp;
/* 227 */ return node;
/* */ }
/* */
/* */ public BTNode getSuccessor(BTNode node, int minmax) {
/* 231 */ return ((minmax == 1) ? node.prevInO() : node.nextInO());
/* */ }
/* */
/* */ public void swapData(BTNode node1, BTNode node2)
/* */ {
/* 237 */ BTData data = node1.getData();
/* 238 */ node1.setData(node2.getData());
/* 239 */ node2.setData(data);
/* */ }
/* */
/* */ public void deleteAll()
/* */ {
/* 245 */ for (BTNode node = this.root.firstPoO(); node != null; )
/* */ {
/* 247 */ BTNode leaf = node;
/* 248 */ node = leaf.nextPoO();
/* 249 */ destroy(leaf);
/* */ }
/* 251 */ this.root = null;
/* */ }
/* */
/* */ public BTNode locateBST(BTData data)
/* */ {
/* 260 */ for (BTNode node = this.root; node != null; )
/* */ {
/* 262 */ int side = node.compareSide(data);
/* 263 */ if (side == 0)
/* */ break;
/* 265 */ node = node.getChild(side);
/* */ }
/* 267 */ return node;
/* */ }
/* */
/* */ public BTNode insertBST(BTData data)
/* */ {
/* 272 */ if (this.root == null)
/* 273 */ return add(null, 0, data);
/* 274 */ BTNode node = locate(data);
/* 275 */ return ((node != null) ? null : add(this.lastnode, this.nextside, data));
/* */ }
/* */
/* */ public BTNode deleteBST(BTData data, int minmax)
/* */ {
/* 280 */ BTNode node = locate(data);
/* 281 */ if (node == null)
/* 282 */ return null;
/* 283 */ if (node.hasTwoChildren())
/* 284 */ node = swap(node, minmax);
/* 285 */ return remove(node);
/* */ }
/* */
/* */ public BTNode insertAVL(BTData data)
/* */ {
/* 297 */ if (this.root == null)
/* 298 */ return add(null, 0, data);
/* 299 */ if (locate(data) != null)
/* 300 */ return null;
/* 301 */ BTNode node = add(this.lastnode, this.nextside, data);
/* 302 */ rebalanceAVL(this.lastnode, this.nextside, 1);
/* 303 */ return node;
/* */ }
/* */
/* */ public BTNode deleteAVL(BTData data, int minmax)
/* */ {
/* 315 */ BTNode node = locate(data);
/* 316 */ if (node == null) {
/* 317 */ return null;
/* */ }
/* 319 */ if (node.hasTwoChildren()) {
/* 320 */ node = swap(node, minmax);
/* */ }
/* 322 */ int side = node.getSide();
/* 323 */ node = remove(node);
/* 324 */ rebalanceAVL(node, side, -1);
/* 325 */ return node;
/* */ }
/* */
/* */ public void rebalanceAVL(BTNode node, int side, int in)
/* */ {
/* 333 */ for (; node != null; node = node.getParent())
/* */ {
/* 335 */ if (node.getBalance() != in * side)
/* 336 */ node.setBalance(node.getBalance() + in * side);
/* */ else {
/* 338 */ node = rotateAVL(node);
/* */ }
/* 340 */ if ((in == 1) && (node.getBalance() == 0)) return; if ((in == -1) &&
(node.getBalance() != 0))
/* */ return;
/* 342 */ side = node.getSide();
/* */ }
/* */ }
/* */
/* */ public BTNode rotateAVL(BTNode node)
/* */ {
/* 357 */ int side = node.getBalance();
/* 358 */ BTNode child = node.getChild(side);
/* */
/* 360 */ if (child.getBalance() == -side)
/* */ {
/* 362 */ BTNode grand = child.getChild(-side);
/* 363 */ if (grand.getBalance() == -side)
/* */ {
/* 365 */ grand.setBalance(0);
/* 366 */ child.setBalance(side);
/* 367 */ node.setBalance(0);
/* */ }
/* 369 */ else if (grand.getBalance() == side)
/* */ {
/* 371 */ grand.setBalance(0);
/* 372 */ child.setBalance(0);
/* 373 */ node.setBalance(-side);
/* */ }
/* */ else {
/* 376 */ node.setBalance(0);
/* 377 */ child.setBalance(0);
/* */ }
/* 379 */ rotate(child, side);
/* */ }
/* 382 */ else if (child.getBalance() == side)
/* */ {
/* 384 */ node.setBalance(0);
/* 385 */ child.setBalance(0);
/* */ }
/* 387 */ else if (child.getBalance() == 0)
/* */ {
/* 389 */ node.setBalance(side);
/* 390 */ child.setBalance(-side);
/* */ }
/* 392 */ node = rotate(node, -side);
/* 393 */ return node;
/* */ }
/* */
/* */ public void balanceAVL(BTNode node)
/* */ {
/* 400 */ int side = node.getBalance();
/* 401 */ BTNode child = node.getChild(side);
/* 402 */ if (child.getBalance() == -side)
/* */ {
/* 404 */ BTNode grand = child.getChild(-side);
/* 405 */ if (grand.getBalance() == -side)
/* */ {
/* 407 */ grand.setBalance(0);
/* 408 */ child.setBalance(side);
/* 409 */ node.setBalance(0);
/* */ }
/* 411 */ else if (grand.getBalance() == side)
/* */ {
/* 413 */ grand.setBalance(0);
/* 414 */ child.setBalance(0);
/* 415 */ node.setBalance(-side);
/* */ }
/* */ else {
/* 418 */ node.setBalance(0);
/* 419 */ child.setBalance(0);
/* */ }
/* */
/* */ }
/* 423 */ else if (child.getBalance() == side)
/* */ {
/* 425 */ child.setBalance(0);
/* 426 */ node.setBalance(0);
/* */ } else {
/* 428 */ if (child.getBalance() != 0)
/* */ return;
/* 430 */ child.setBalance(-side);
/* */ }
/* */ }
/* */
/* */ public boolean isAVLcompliant(BTNode node)
/* */ {
/* 440 */ boolean balanced = true;
/* */
/* 442 */ if (node == null)
/* 443 */ return true;
/* 444 */ int l = getHeight(node.getChild(-1), 0);
/* 445 */ int r = getHeight(node.getChild(1), 0);
/* 446 */ node.setBalance(r - l);
/* 447 */ if ((r - l > 1) || (r - l < -1))
/* 448 */ balanced = false;
/* 449 */ return ((balanced) && (isAVLcompliant(node.getChild(-1))) && (isAVLcompliant
(node.getChild(1))));
/* */ }
/* */
/* */ public int getHeight(BTNode node, int depth)
/* */ {
/* 454 */ if (node == null)
/* 455 */ return 0;
/* 456 */ if (node.isLeaf()) {
/* 457 */ return (depth + 1);
/* */ }
/* */
/* 460 */ int lmax = getHeight(node.getChild(-1), depth + 1);
/* 461 */ int rmax = getHeight(node.getChild(1), depth + 1);
/* 462 */ return ((lmax > rmax) ? lmax : rmax);
/* */ }
/* */
/* */ public BTNode insertSPL(BTData data)
/* */ {
/* 474 */ if (this.root == null)
/* 475 */ return add(null, 0, data);
/* 476 */ BTNode node = locate(data);
/* 477 */ splay(this.lastnode);
/* 478 */ return ((node != null) ? null : splitinsert(data));
/* */ }
/* */
/* */ public BTNode splitinsert(BTData data)
/* */ {
/* 483 */ BTNode node = new BTNode(data);
/* 484 */ int side = -this.root.compareSide(data);
/* 485 */ BTNode child = this.root.getChild(-side);
/* */
/* 487 */ this.root.setChild(-side, null);
/* 488 */ link(node, side, this.root);
/* 489 */ link(node, -side, child);
/* 490 */ this.root = node;
/* 491 */ return this.root;
/* */ }
/* */
/* */ public BTNode deleteSPL(BTData data, int minmax)
/* */ {
/* 498 */ BTNode node = locate(data);
/* 499 */ splay(this.lastnode);
/* 500 */ if (node == null)
/* 501 */ return null;
/* 502 */ BTNode root = node;
/* 503 */ node = getSuccessor(root, minmax);
/* 504 */ if (node != null)
/* 505 */ splay(node);
/* 506 */ return remove(root);
/* */ }
/* */
/* */ public void splay(BTNode node)
/* */ {
/* 516 */ while (node != this.root)
/* */ {
/* 518 */ BTNode parent = node.getParent();
/* 519 */ BTNode grandparent = parent.getParent();
/* 520 */ int side = node.getSide();
/* 521 */ if (grandparent == null) {
/* 522 */ rotate(parent, -side);
/* */ }
/* 524 */ else if (parent.getSide() == side)
/* */ {
/* 526 */ rotate(grandparent, -side);
/* 527 */ rotate(parent, -side);
/* */ }
/* */ else {
/* 530 */ if (parent.getSide() == side)
/* */ continue;
/* 532 */ rotate(parent, -side);
/* 533 */ rotate(grandparent, side);
/* */ }
/* */ }
/* */ }
/* */
/* */ public boolean isSPLcompliant()
/* */ {
/* 541 */ return true;
/* */ }
/* */
/* */ public BTNode insertRBL(BTData data)
/* */ {
/* 552 */ if (this.root == null)
/* */ {
/* 554 */ this.root = add(null, 0, data);
/* 555 */ this.root.setColor(2);
/* 556 */ return this.root;
/* */ }
/* 558 */ if (locate(data) != null)
/* 559 */ return null;
/* 560 */ BTNode node = add(this.lastnode, this.nextside, data);
/* 561 */ node.setColor(1);
/* 562 */ fixRBinsert(node);
/* 563 */ return node;
/* */ }
/* */
/* */ public void fixRBinsert(BTNode node)
/* */ {
/* 571 */ while (node != this.root)
/* */ {
/* 573 */ BTNode parent = node.getParent();
/* 574 */ if (parent.getColor() == 2)
/* */ break;
/* 576 */ BTNode grandparent = parent.getParent();
/* 577 */ int side = parent.getSide();
/* 578 */ BTNode uncle = grandparent.getChild(-side);
/* 579 */ if ((uncle != null) && (uncle.getColor() == 1))
/* */ {
/* 581 */ parent.setColor(2);
/* 582 */ uncle.setColor(2);
/* 583 */ grandparent.setColor(1);
/* 584 */ node = grandparent;
/* */ }
/* 586 */ else if (node.getSide() == -side)
/* */ {
/* 588 */ rotate(parent, side);
/* 589 */ node = parent;
/* */ } else {
/* 591 */ if (node.getSide() != side)
/* */ continue;
/* 593 */ parent.setColor(2);
/* 594 */ grandparent.setColor(1);
/* 595 */ rotate(grandparent, -side);
/* */ }
/* */ }
/* 598 */ this.root.setColor(2);
/* */ }
/* */
/* */ public BTNode deleteRBL(BTData data, int minmax)
/* */ {
/* 606 */ BTNode node = locate(data);
/* 607 */ if (node == null) {
/* 608 */ return null;
/* */ }
/* 610 */ if (node.hasTwoChildren()) {
/* 611 */ node = swap(node, minmax);
/* */ }
/* 613 */ int color = node.getColor();
/* 614 */ int side = node.getSide();
/* 615 */ node = remove(node);
/* 616 */ if ((this.root != null) && (side == 0)) {
/* 617 */ this.root.setColor(2);
/* */ }
/* 619 */ else if ((node != null) && (color == 2))
/* 620 */ fixRBdelete(node, side);
/* 621 */ return node;
/* */ }
/* */
/* */ public void fixRBdelete(BTNode parent, int side)
/* */ {
/* 629 */ BTNode node = parent.getChild(side);
/* 630 */ if ((node != null) && (node.getColor() == 1))
/* */ {
/* 632 */ node.setColor(2);
/* 633 */ return;
/* */ }
/* */
/* */ do
/* */ {
/* 638 */ if (node != null)
/* */ {
/* 640 */ parent = node.getParent();
/* 641 */ side = node.getSide();
/* */ }
/* 643 */ BTNode sibling = parent.getChild(-side);
/* 644 */ BTNode nephew = sibling.getChild(side);
/* 645 */ BTNode niece = sibling.getChild(-side);
/* */
/* 647 */ if (sibling.getColor() == 1)
/* */ {
/* 649 */ sibling.setColor(2);
/* 650 */ parent.setColor(1);
/* 651 */ rotate(parent, side);
/* */ }
/* 654 */ else if ((isBlack(nephew)) && (isBlack(niece)))
/* */ {
/* 656 */ sibling.setColor(1);
/* 657 */ node = (node == null) ? parent : node.getParent();
/* */ }
/* 660 */ else if ((isBlack(niece)) && (isRed(nephew)))
/* */ {
/* 662 */ sibling.setColor(1);
/* 663 */ nephew.setColor(2);
/* 664 */ rotate(sibling, -side);
/* */ }
/* */ else {
/* 667 */ if (!(isRed(niece)))
/* */ continue;
/* 669 */ sibling.setColor(parent.getColor());
/* 670 */ parent.setColor(2)
;
/* 671 */ niece.setColor(2);
/* 672 */
rotate(parent, side);
/* 673 */
node = this.root;
/* */
}
/* */
}
/* 636 */
while ((node != this.root) && (isBlack(node)));
/* */
/* 676 */ node.setColor(2);
/* */ }
/* */
/* */ public boolean isRed(BTNode node)
/* */ {
/* 681 */
return ((node != null) && (node.getColor() == 1));
/* */
}
/* */
/* */ public boolean isBlack(BTNode node) {
/* 685 */
return ((node == null) || (node.getColor() == 2));
/* */
}
/* */
/* */ public boolean isRBLcompliant(BTNode node)
/* */ {
/* 690 */ return false;
/* */ }
/* */ }
Isso é implementação completa. Boa sorte.
Você não pode navegar para o nó e vincular seus filhos aos pais do nó para não quebrar a árvore? A ideia é
- Encontre o nó
- salvar referência aos seus filhos
- salvar referência aos seus pais
- vincular o pai aos filhos do nó
- Somente então remova o nó (grátis)
Como é explicado melhor em Wikipedia, você deve ter cuidado e determinar quantos filhos eles têm. Depois disso, é bem direto.
Eu faria uma caminhada na ordem, isso oferece uma lista de pedidos de todos os itens. Em seguida, construa a árvore novamente.
Ou se você precisar fazer isso com frequência, talvez um Árvore AVL é melhor.
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