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二叉查找树的Java实现
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轉(zhuǎn)自：http://blog.csdn.net/lovesqcc/article/details/6246615
為了克服對(duì)樹(shù)結(jié)構(gòu)編程的恐懼感，決心自己實(shí)現(xiàn)一遍二叉查找樹(shù)，以便掌握關(guān)于樹(shù)結(jié)構(gòu)編程的一些技巧和方法。以下是基本思路：
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??????? [1] 關(guān)于容器與封裝。封裝，是一種非常重要的系統(tǒng)設(shè)計(jì)思想；無(wú)論是面向過(guò)程的函數(shù)，還是面向?qū)ο蟮膶?duì)象，都是實(shí)現(xiàn)抽象和封裝的技術(shù)手段。要使系統(tǒng)更加安全更具可維護(hù)性，就應(yīng)當(dāng)將封裝思想謹(jǐn)記心中。容器是封裝思想的絕好示例。用戶對(duì)容器的印象應(yīng)該簡(jiǎn)潔地表達(dá)為：A. 可以存入指定的東西； B. 可以取出所期望的東西。 而至于這容器中究竟有什么機(jī)關(guān)，藏的是毒蛇還是黃金，都是對(duì)用戶不可見(jiàn)的。二叉查找樹(shù)就是這樣一個(gè)容器。面向?qū)ο缶幊讨?#xff0c;為實(shí)現(xiàn)樹(shù)結(jié)構(gòu)，自然要對(duì)樹(shù)結(jié)點(diǎn)對(duì)象進(jìn)行建模。這里采用了內(nèi)部類(lèi)；外部類(lèi)對(duì)二叉查找樹(shù)進(jìn)行建模，而樹(shù)結(jié)點(diǎn)作為內(nèi)部類(lèi)實(shí)現(xiàn)。
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?????? [2] 本程序盡量實(shí)現(xiàn)一個(gè)比較實(shí)用的二叉查找樹(shù)，其中包括動(dòng)態(tài)的插入、刪除操作；查詢給定關(guān)鍵字、最小關(guān)鍵字、最大關(guān)鍵字；獲取二叉樹(shù)的有序列表（用于排序）等。因?yàn)槲蚁Ｍ院筮€能用到這個(gè)容器的，而不僅僅是編程練習(xí)。二叉查找樹(shù)操作的大部分算法參考了《算法導(dǎo)論2》第12章內(nèi)容，刪除操作略顯笨拙。程序中有錯(cuò)誤之處，歡迎指出。
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????? [3]? 程序如下：
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[c-sharp]?view plaincopyprint?
?????????package?datastructure.tree;??import?java.util.ArrayList;??import?java.util.List;????public?class?BinarySearchTree?{??????????????????private?TreeNode?root?=?null;??????????????????private?List<TreeNode>?nodelist?=?new?ArrayList<TreeNode>();????????????private?class?TreeNode?{????????????????????private?int?key;??????????private?TreeNode?leftChild;??????????private?TreeNode?rightChild;??????????private?TreeNode?parent;????????????????????public?TreeNode(int?key,?TreeNode?leftChild,?TreeNode?rightChild,?TreeNode?parent)?{??????????????this.key?=?key;??????????????this.leftChild?=?leftChild;??????????????this.rightChild?=?rightChild;??????????????this.parent?=?parent;??????????}?????????????public?int?getKey()?{??????????????return?key;??????????}??????????public?String?toString()??????????{??????????????String?leftkey?=?(leftChild?==?null???""?:?String.valueOf(leftChild.key));????????????????String?rightkey?=?(rightChild?==?null???""?:?String.valueOf(rightChild.key));???????????????return?"("?+?leftkey?+?"?,?"?+?key?+?"?,?"?+?rightkey?+?")";??????????}????????????????}?????????????????????public?boolean?isEmpty()??????{??????????if?(root?==?null)?{??????????????return?true;??????????}?else?{??????????????return?false;??????????}?????????????????}????????????????????public?void?TreeEmpty()?throws?Exception???????{??????????if?(isEmpty())?{??????????????throw?new?Exception("樹(shù)為空!");??????????}??????}??????????????????????public?TreeNode?search(int?key)???????{??????????TreeNode?pNode?=?root;??????????while?(pNode?!=?null?&&?pNode.key?!=?key)?{??????????????if?(key?<?pNode.key)?{??????????????????pNode?=?pNode.leftChild;??????????????}??????????????else?{??????????????????pNode?=?pNode.rightChild;??????????????}??????????}??????????return?pNode;??????}??????????????????????public?TreeNode?minElemNode(TreeNode?node)?throws?Exception??????{??????????if?(node?==?null)?{??????????????throw?new?Exception("樹(shù)為空！");??????????}??????????TreeNode?pNode?=?node;??????????while?(pNode.leftChild?!=?null)?{??????????????pNode?=?pNode.leftChild;??????????}??????????return?pNode;??????}??????????????????????public?TreeNode?maxElemNode(TreeNode?node)?throws?Exception???????{??????????if?(node?==?null)?{??????????????throw?new?Exception("樹(shù)為空！");??????????}??????????TreeNode?pNode?=?node;??????????while?(pNode.rightChild?!=?null)?{??????????????pNode?=?pNode.rightChild;??????????}??????????return?pNode;??????}???????????????????????public?TreeNode?successor(TreeNode?node)?throws?Exception??????{??????????if?(node?==?null)?{??????????????return?null;??????????}??????????????????????????????if?(node.rightChild?!=?null)?{???????????????return?minElemNode(node.rightChild);??????????}????????????????????TreeNode?parentNode?=?node.parent;??????????while?(parentNode?!=?null?&&?node?==?parentNode.rightChild)?{??????????????node?=?parentNode;??????????????parentNode?=?parentNode.parent;??????????}??????????return?parentNode;??????}?????????????????????????????public?TreeNode?precessor(TreeNode?node)?throws?Exception??????{??????????if?(node?==?null)?{??????????????return?null;??????????}??????????????????????????????if?(node.leftChild?!=?null)?{???????????????return?maxElemNode(node.leftChild);??????????}????????????????????TreeNode?parentNode?=?node.parent;??????????while?(parentNode?!=?null?&&?node?==?parentNode.leftChild)?{??????????????node?=?parentNode;??????????????parentNode?=?parentNode.parent;??????????}??????????return?parentNode;??????}???????????????????????????public?void?insert(int?key)??????{??????????TreeNode?parentNode?=?null;??????????TreeNode?newNode?=?new?TreeNode(key,?null,?null,null);??????????TreeNode?pNode?=?root;??????????if?(root?==?null)?{??????????????root?=?newNode;??????????????return?;??????????}??????????while?(pNode?!=?null)?{??????????????parentNode?=?pNode;??????????????if?(key?<?pNode.key)?{?????????????????????pNode?=?pNode.leftChild;??????????????}??????????????else?if?(key?>?pNode.key)?{??????????????????pNode?=?pNode.rightChild;??????????????}?else?{????????????????????????????????????return?;??????????????}??????????}??????????if?(key?<?parentNode.key)?{??????????????parentNode.leftChild?=?newNode;??????????????newNode.parent?=?parentNode;??????????}??????????else?{??????????????parentNode.rightChild?=?newNode;??????????????newNode.parent?=?parentNode;??????????}???????????????????????}?????????????????????public?void?delete(int?key)?throws?Exception??????{??????????TreeNode?pNode?=?search(key);??????????if?(pNode?==?null)?{??????????????throw?new?Exception("樹(shù)中不存在要?jiǎng)h除的關(guān)鍵字!");??????????}??????????delete(pNode);??????}????????????????????????private?void?delete(TreeNode?pNode)?throws?Exception???????{????????????if?(pNode?==?null)?{????????????????return?;????????????}????????????if?(pNode.leftChild?==?null?&&?pNode.rightChild?==?null)?{?????????????????TreeNode?parentNode?=?pNode.parent;????????????????if?(pNode?==?parentNode.leftChild)?{????????????????????parentNode.leftChild?=?null;????????????????}?else?{????????????????????parentNode.rightChild?=?null;????????????????}????????????????return?;????????????}????????????if?(pNode.leftChild?==?null?&&?pNode.rightChild?!=?null)?{?????????????????TreeNode?parentNode?=?pNode.parent;????????????????if?(pNode?==?parentNode.leftChild)?{????????????????????parentNode.leftChild?=?pNode.rightChild;????????????????????pNode.rightChild.parent?=?parentNode;????????????????}????????????????else?{????????????????????parentNode.rightChild?=?pNode.rightChild;????????????????????pNode.rightChild.parent?=?parentNode;????????????????}????????????????return?;????????????}????????????if?(pNode.leftChild?!=?null?&&?pNode.rightChild?==?null)?{?????????????????TreeNode?parentNode?=?pNode.parent;????????????????if?(pNode?==?parentNode.leftChild)?{????????????????????parentNode.leftChild?=?pNode.leftChild;????????????????????pNode.rightChild.parent?=?parentNode;????????????????}????????????????else?{????????????????????parentNode.rightChild?=?pNode.leftChild;????????????????????pNode.rightChild.parent?=?parentNode;????????????????}????????????????return?;????????????}????????????????????????TreeNode?successorNode?=?successor(pNode);????????????delete(successorNode);????????????pNode.key?=?successorNode.key;??????}?????????????????????public?List<TreeNode>?inOrderTraverseList()??????{??????????if?(nodelist?!=?null)?{?????????????nodelist.clear();??????????}??????????inOrderTraverse(root);??????????return?nodelist;??????}?????????????????????private?void?inOrderTraverse(TreeNode?root)??????{??????????if?(root?!=?null)?{??????????????inOrderTraverse(root.leftChild);??????????????nodelist.add(root);??????????????inOrderTraverse(root.rightChild);??????????}??????}?????????????????????public?String?toStringOfOrderList()??????{??????????StringBuilder?sbBuilder?=?new?StringBuilder("?[?");??????????for?(TreeNode?p:?inOrderTraverseList())?{??????????????sbBuilder.append(p.key);??????????????sbBuilder.append("?");??????????}??????????sbBuilder.append("]");??????????return?sbBuilder.toString();??????}????????????????????public?String?toString()??????{??????????StringBuilder?sbBuilder?=?new?StringBuilder("?[?");??????????for?(TreeNode?p:?inOrderTraverseList())?{??????????????sbBuilder.append(p);??????????????sbBuilder.append("?");??????????}??????????sbBuilder.append("]");??????????return?sbBuilder.toString();??????}??????public?TreeNode?getRoot()?{??????????return?root;??????}????????????public?static?void?testNode(BinarySearchTree?bst,?TreeNode?pNode)?throws?Exception?{??????????System.out.println("本結(jié)點(diǎn):?"?+?pNode);??????????System.out.println("前趨結(jié)點(diǎn):?"?+?bst.precessor(pNode));??????????System.out.println("后繼結(jié)點(diǎn):?"?+?bst.successor(pNode));??????}????????????public?static?void?testTraverse(BinarySearchTree?bst)?{??????????System.out.println("二叉樹(shù)遍歷："?+?bst);??????????System.out.println("二叉查找樹(shù)轉(zhuǎn)換為有序列表:?"?+?bst.toStringOfOrderList());??????}????????????public?static?void?main(String[]?args)???????{??????????try?{??????????????BinarySearchTree?bst?=?new?BinarySearchTree();??????????????System.out.println("查找樹(shù)是否為空？?"?+?(bst.isEmpty()???"是"?:?"否"));??????????????int[]?keys?=?new?int[]?{15,?6,?18,?3,?7,?13,?20,?2,?9,?4};??????????????for?(int?key:?keys)?{??????????????????bst.insert(key);??????????????}??????????????System.out.println("查找樹(shù)是否為空？?"?+?(bst.isEmpty()???"是"?:?"否"));????????????????????????????TreeNode?minkeyNode?=?bst.minElemNode(bst.getRoot());??????????????System.out.println("最小關(guān)鍵字：?"?+?minkeyNode.getKey());??????????????testNode(bst,?minkeyNode);????????????????????????????TreeNode?maxKeyNode?=?bst.maxElemNode(bst.getRoot());??????????????System.out.println("最大關(guān)鍵字：?"?+?maxKeyNode.getKey());??????????????testNode(bst,?maxKeyNode);????????????????????????????System.out.println("根結(jié)點(diǎn)關(guān)鍵字：?"?+?bst.getRoot().getKey());??????????????testNode(bst,?bst.getRoot());??????????????testTraverse(bst);????????????????????????????System.out.println("******************************?");????????????????????????????System.out.println("查找?7?:?"?+?(bst.search(7)?!=?null???"查找成功!"?:?"查找失敗，不存在該關(guān)鍵字!"));??????????????bst.delete(7);??????????????System.out.println("查找?7?:?"?+?(bst.search(7)?!=?null???"查找成功!"?:?"查找失敗，不存在該關(guān)鍵字!"));??????????????System.out.println("查找?12?:?"?+?(bst.search(12)?!=?null???"查找成功!"?:?"查找失敗，不存在該關(guān)鍵字!"));??????????????bst.insert(12);??????????????System.out.println("查找?12?:?"?+?(bst.search(12)?!=?null???"查找成功!"?:?"查找失敗，不存在該關(guān)鍵字!"));????????????????????????????testTraverse(bst);????????????????????????????System.out.println("******************************?");????????????????????????????bst.insert(16);??????????????bst.delete(6);??????????????bst.delete(4);????????????????????????????testTraverse(bst);????????????????????????}?catch?(Exception?e)?{??????????????System.out.println(e.getMessage());??????????????e.printStackTrace();??????????}??????}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轉(zhuǎn)載于:https://www.cnblogs.com/cugwx/p/3664306.html
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