新增二分搜索树查询，删除

Author: tianqing.liang

01Linear-Search/LinearSearch.dart renamed to 01-Linear-Search/LinearSearch.dart

@@ -1,3 +1,5 @@
+import 'LinkedListStatck.dart';
+import 'LinkedListQueue.dart';
 /**
  * 二分搜索树
  */
@@ -151,6 +153,113 @@ class BST<T extends Comparable<T>> {
     print(node.e);
   }
 
+  // 二分搜索树的非递归前序遍历
+  preOrderNR() {
+    if (root == null) return;
+    LinkedListStack stack = new LinkedListStack();
+    stack.push(root);
+    while (!stack.isEmpty()) {
+      _Node cur = stack.pop();
+      print(cur.e);
+      if (cur.right != null) {
+        stack.push(cur.right);
+      }
+      if (cur.left != null){
+        stack.push(cur.left);
+      }
+    }
+  }
+
+  // 二分搜索树的层序遍历
+  levelOrder(){
+    if(root == null)
+      return;
+    LinkedListQueue q= new LinkedListQueue();
+    q.enqueue(root);
+    while(!q.isEmpty()){
+      _Node cur = q.dequeue();
+      print(cur.e);
+      if(cur.left != null){
+        q.enqueue(cur.left);
+      }
+      if(cur.right != null){
+        q.enqueue(cur.right);
+      }
+    }
+  }
+
+  // 寻找二分搜索树的最小元素
+  searchMinimum<T>(){
+    if(size == 0){
+      throw new Exception("BST is empty!");
+    }
+    return _minimum(root!).e;
+  }
+  // 返回以node为根的二分搜索树的最小值所在的节点
+  _Node _minimum(_Node node){
+    if(node.left == null){
+      return node;
+    }
+    return _minimum(node.left!);
+  }
+
+  // 寻找二分搜索树的最大元素
+  searchMaximum<T>(){
+    if(size == 0){
+      throw new Exception("BST is empty");
+    }
+    return _maximum(root!).e;
+  }
+  // 返回以node为根的二分搜索树的最大值所在的节点
+  _Node _maximum(_Node node){
+    if(node.right == null){
+      return node;
+    }
+    return _maximum(node.right!);
+  }
+
+  // 从二分搜索树中删除最小值所在节点, 返回最小值
+  removeMin<T>(){
+    T ret = searchMinimum();
+    root = _removeMinDetail(root!);
+    return ret;
+  }
+  // 删除掉以node为根的二分搜索树中的最小节点
+  // 返回删除节点后新的二分搜索树的根
+  _Node _removeMinDetail(_Node node){
+    if(node.left == null){
+      _Node rightNode = node.right!;
+      node.right = null;
+      size = size! - 1;
+      return rightNode;
+    }
+    node.left = _removeMinDetail(node.left!);
+    return node;
+  }
+
+
+  // 从二分搜索树中删除最大值所在节点
+  removeMax<T>(){
+    T ret = searchMaximum();
+    root = _removeMaxDetail(root!);
+    return ret;
+  }
+  // 删除掉以node为根的二分搜索树中的最大节点
+  // 返回删除节点后新的二分搜索树的根
+  _Node _removeMaxDetail(_Node node){
+    if(node.right == null){
+      _Node leftNode = node.left!;
+      node.left = null;
+      size = size! -1 ;
+      return leftNode;
+    }
+    node.right = _removeMaxDetail(node.right!);
+    return node;
+  }
+
+
+
+
   @override
   String toString() {
     StringBuffer res = new StringBuffer();

02Selection-Sort/Selection-sort.dart renamed to 02-Selection-Sort/Selection-sort.dart

@@ -0,0 +1,143 @@
+class LinkedList<T> {
+  _Node? _dummyHead;
+  late int _size;
+
+  LinkedList() {
+    _dummyHead = new _Node.withEmpty();
+    _size = 0;
+  }
+
+  int getSize() {
+    return _size;
+  }
+
+  bool isEmpty() {
+    return _size == 0;
+  }
+
+  remove(int index){
+    if (index < 0 || index > _size) {
+      throw Exception("Remove Failed,Illegal index");
+    }
+    _Node? prev = _dummyHead;
+    for(var i =0;i<index ;i++){
+      prev = prev?.next;
+    }
+    _Node? retNode = prev!.next;
+    prev.next = retNode!.next;
+    retNode.next = null;
+    _size --;
+    return retNode.t;
+  }
+
+  //从链表中删除第一个元素，返回删除元素
+  T? removeFirst(){
+    remove(0);
+  }
+  //从链表中删除第一个元素，返回删除元素
+  T? removeLast(){
+    remove(_size -1);
+  }
+
+
+  //在链表的index位置添加新的元素e
+  add(int index, T t) {
+    if (index < 0 || index > _size) {
+      throw Exception("Add Failed,Illegal index");
+    }
+//      if(index == 0){
+//         addFirst(t);
+//      }else{
+    _Node? prev = _dummyHead;
+    for (var i = 0; i < index; i++) {
+      prev = prev?.next;
+    }
+    _Node _node = new _Node.wihtHead(t);
+    _node.next = prev?.next;
+    prev?.next = _node;
+    _size++;
+//      }
+  }
+
+  addLast(T t) {
+    add(_size, t);
+  }
+
+  addFirst(T t) {
+//      _Node _node =new _Node.head(t);
+//      _node.next = _head;
+//      _head = _node;
+    add(0, t);
+  }
+
+  //获取链表第index位置的元素
+  T get(int index){
+    if (index < 0 || index > _size) {
+      throw Exception("Get Failed,Illegal index");
+    }
+    _Node? cur = _dummyHead!.next;
+    for(var i=0;i<index;i++){
+      cur = cur!.next;
+    }
+    return cur!.t;
+  }
+
+  T getFirst(){
+    return get(0);
+  }
+  T getLast(){
+    return get(_size-1);
+  }
+  set(int index,T t){
+    if (index < 0 || index > _size) {
+      throw Exception("Set Failed,Illegal index");
+    }
+    _Node? cur = _dummyHead!.next;
+    for(var i =0;i<index;i++){
+      cur = cur!.next;
+    }
+    cur!.t= t;
+  }
+
+  bool contains(T t){
+    _Node? cur = _dummyHead!.next;
+    for(var i =0;i<_size-1;i++){
+      if(cur!.t.compareTo(t)){
+        return true;
+      }
+      cur = cur.next;
+    }
+    return false;
+  }
+
+  @override
+  String toString() {
+    StringBuffer res =new StringBuffer();
+    for(_Node? cur = _dummyHead!.next ; cur != null ; cur = cur.next){
+      res.write(cur);
+      res.write("->");
+    }
+    res.write("NULL");
+    return res.toString();
+  }
+}
+//节点
+class _Node<T> {
+   _Node? next;
+
+  T? t;
+
+  _Node.withEmpty();
+
+  _Node.withAll(this.t, this.next);
+
+  factory _Node.wihtHead(T t) {
+    var result = new _Node.withAll(t,  null);
+    return result;
+  }
+
+  @override
+  String toString() {
+    return t.toString();
+  }
+}

03Insertion-Sort/ArrayGenerator.dart renamed to 03-Insertion-Sort/ArrayGenerator.dart

@@ -0,0 +1,108 @@
+import 'Queue.dart';
+
+/**
+ * 带尾结点的队列
+ */
+class LinkedListQueue implements Queue{
+
+  late _Node? _head;
+  late _Node? _tail;
+  late int _size;
+
+  LinkedListQueue(){
+    _head = null;
+    _tail = null;
+    _size = 0;
+  }
+
+  @override
+  dequeue() {
+    if (isEmpty()) {
+      throw Exception("Cannot dequeue from an empty queue");
+    }
+    _Node retNode = _head!;
+    _head = _head!.next;
+    retNode.next = null;
+    if(_head == null){
+      _tail =null;
+    }
+    _size --;
+    return retNode.t;
+  }
+
+  @override
+  void enqueue(e) {
+    if(_tail == null){
+      _tail = _Node.wihtHead(e);
+      _head = _tail;
+    }else{
+    _tail!.next =_Node.wihtHead(e);
+    _tail = _tail!.next;
+    }
+    _size++;
+  }
+
+  @override
+  getFront() {
+    if (isEmpty()) {
+      throw Exception("Queue is empty");
+    }
+    return _head!.t;
+  }
+
+  @override
+  int getSize() {
+    return _size;
+  }
+
+  @override
+  bool isEmpty() {
+    return _size == 0;
+  }
+
+  @override
+  String toString() {
+    StringBuffer res =new StringBuffer();
+    res.write("Queue: front ");
+    for(_Node? cur = _head!.next ; cur != null ; cur = cur.next){
+      res.write(cur);
+      res.write("->");
+    }
+    res.write("NULL tail");
+    return res.toString();
+  }
+
+}
+
+//节点
+class _Node<T> {
+  _Node? next;
+
+  T? t;
+
+  _Node();
+
+  _Node.withAll(this.t, this.next);
+
+  factory _Node.wihtHead(T t) {
+    var result = new _Node.withAll(t,  null);
+    return result;
+  }
+
+  @override
+  String toString() {
+    return t.toString();
+  }
+}
+
+void main(){
+  LinkedListQueue queue = new LinkedListQueue();
+  for(int i = 0 ; i < 10 ; i ++){
+    queue.enqueue(i);
+    print(queue);
+    if(i % 3 ==2){
+      queue.dequeue();
+      print(queue);
+    }
+  }
+}