链表,链表实现栈，链表实现队列

Author: tianqing.liang

05LinkedList/LinkedList.dart

@@ -1,70 +1,143 @@
-class LinkedList<T>{
+class LinkedList<T> {
+  _Node? _dummyHead;
+  late int _size;
 
-   late _Node _head;
-   late int _size;
+  LinkedList() {
+    _dummyHead = new _Node.all(null,null);
+    _size = 0;
+  }
 
-   LinkedList(){
-      _head = new _Node.empty();
-      _size = 0;
-   }
+  int getSize() {
+    return _size;
+  }
 
-   int getSize(){
-      return _size;
-   }
+  bool isEmpty() {
+    return _size == 0;
+  }
 
-   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);
+  }
 
-   addFirst(T t){
+
+  //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.head(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);
+  }
 
-      _head = new _Node.all(t, _head);
-      _size++;
-   }
+  //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;
+  }
 
-   //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 = _head;
-         for(var i =0;i<index-1;i++){
-            prev = prev.next;
-         }
-         _Node _node = new _Node.head(t);
-         _node.next = prev.next;
-         prev.next = _node;
-         _size++;
+  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;
+  }
 
-   addLast(T t){
-      add(_size, t);
-   }
+  @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>{
-   late _Node next;
-   late T t;
+class _Node<T> {
+   _Node? next;
 
-   _Node.empty();
+  T? t;
 
-   _Node.all(this.t,this.next);
+  _Node.empty();
 
-   factory _Node.head(T t){
-      dynamic i ;
-      var result = new _Node.all(t, i);
-      return result;
-   }
+  _Node.all(this.t, this.next);
 
-   @override
+  factory _Node.head(T t) {
+    var result = new _Node.all(t,  null);
+    return result;
+  }
+
+  @override
   String toString() {
     return t.toString();
   }
-}
+}

05LinkedList/LinkedListQueue.dart

@@ -0,0 +1,53 @@
+import 'Queue.dart';
+class LinkedListQueue implements Queue{
+  @override
+  dequeue() {
+    // TODO: implement dequeue
+    throw UnimplementedError();
+  }
+
+  @override
+  void enqueue(e) {
+    // TODO: implement enqueue
+  }
+
+  @override
+  getFront() {
+    // TODO: implement getFront
+    throw UnimplementedError();
+  }
+
+  @override
+  int getSize() {
+    // TODO: implement getSize
+    throw UnimplementedError();
+  }
+
+  @override
+  bool isEmpty() {
+    // TODO: implement isEmpty
+    throw UnimplementedError();
+  }
+
+}
+
+//节点
+class _Node<T> {
+  _Node? next;
+
+  T? t;
+
+  _Node.empty();
+
+  _Node.all(this.t, this.next);
+
+  factory _Node.head(T t) {
+    var result = new _Node.all(t,  null);
+    return result;
+  }
+
+  @override
+  String toString() {
+    return t.toString();
+  }
+}

05LinkedList/LinkedListStatck.dart

@@ -0,0 +1,45 @@
+import 'Stack.dart';
+import 'LinkedList.dart';
+
+class LinkedListStack implements Stack{
+
+  LinkedList? _linkedList;
+
+  LinkedListStack(){
+    _linkedList =new LinkedList();
+  }
+
+  @override
+  int getSize() {
+    return _linkedList!.getSize();
+  }
+
+  @override
+  bool isEmpty() {
+    return _linkedList!.isEmpty();
+  }
+
+  @override
+  peek() {
+    return _linkedList!.getFirst();
+  }
+
+  @override
+  pop() {
+    _linkedList!.removeFirst();
+  }
+
+  @override
+  void push(e) {
+    _linkedList!.addFirst(e);
+  }
+
+  @override
+  String toString() {
+    StringBuffer res = new StringBuffer();
+    res.write("Stack:top ");
+    res.write(_linkedList);
+    return res.toString();
+  }
+  
+}

05LinkedList/Queue.dart

@@ -0,0 +1,7 @@
+abstract class Queue<T>{
+  int getSize();
+  bool isEmpty();
+  void enqueue(T e);
+  T dequeue();
+  T getFront();
+}

05LinkedList/Stack.dart

@@ -0,0 +1,7 @@
+abstract class Stack<T>{
+  int getSize();
+  bool isEmpty();
+  void push(T e);
+  T pop();
+  T peek();
+}

05LinkedList/main.dart

@@ -1,5 +1,23 @@
 import 'LinkedList.dart';
-
+import 'LinkedListStatck.dart';
 void main(){
+  LinkedList linkedList = new LinkedList();
+  for(int i = 0 ; i < 5 ; i ++){
+    linkedList.addFirst(i);
+    print(linkedList);
+  }
+  linkedList.add(2, 666);
+  print(linkedList);
+  linkedList.remove(2);
+  print(linkedList);
+  linkedList.removeFirst();
+  print(linkedList);
+  linkedList.removeLast();
+  print(linkedList);
 
+  LinkedListStack stack =new LinkedListStack();
+  for(int i = 0 ; i < 5 ; i ++){
+    stack.push(i);
+    print(stack);
+  }
 }

README.md

@@ -6,5 +6,5 @@
 2. 选择排序
 3. 插入排序
 4. 栈，队列，循环队列
-
+5. 链表，链表实现栈