Stack Queue LoopQueue

Author: tianqing.liang

README.md

@@ -2,10 +2,10 @@
 
 <h3>使用Flutter的Dart语言重写数据结构与算法</h3>
 
-1. [Dart,Python]线性搜索
-2. [Dart,Python]选择排序
-3. [Dart,Python]插入排序
-4. 栈，队列，循环队列
+1. **[Dart,Python]线性搜索**
+2. **[Dart,Python]选择排序**
+3. **[Dart,Python]插入排序**
+4. **[Dart,Python]栈，队列，循环队列**
 5. 链表，链表实现栈，链表实现队列
 6. 递归
 7. 归并排序
@@ -15,8 +15,8 @@
 11. 集合 和 映射
 12. 堆
 13. 优先队列
-14. [Dart,Python]冒泡排序
-15. [Dart,Python]希尔排序
+14. **[Dart,Python]冒泡排序**
+15. **[Dart,Python]希尔排序**
 16. 线段树
 17. Trie字典树
 18. 并查集

dart/04-Stack-Queue/LoopQueue.dart

@@ -1,44 +1,42 @@
 import 'Queue.dart';
 
-class LoopQueue<T> implements Queue<T>{
-
+class LoopQueue<T> implements Queue<T> {
   List? arr;
-  int front = 0,tail=0;
-  int size =0;
+  int front = 0, tail = 0;
+  int size = 0;
 
-  LoopQueue(){
+  LoopQueue() {
     arr = List.filled(10, false);
   }
 
-  LoopQueue.capcity(int capacity){
-    arr = List.filled(capacity+1, false);
-  }
+  // LoopQueue.capcity(int capacity){
+  //   arr = List.filled(capacity+1, false);
+  // }
 
-  int getCapacity(){
+  int getCapacity() {
     //目前这种方式浪费一个空间
-    int capacity =  arr!.length-1;
+    int capacity = arr!.length - 1;
     return capacity;
   }
 
   @override
   dequeue() {
-    if(isEmpty()){
+    if (isEmpty()) {
       throw Exception("Cannot dequeue from an empty queue");
     }
     T ret = arr![front];
     arr![front] = null;
     front = (front + 1) % arr!.length;
     size--;
-    if(size == getCapacity() / 4 && getCapacity() / 2 != 0){
-      resize((getCapacity()/2) as int);
+    if (size == getCapacity() / 4 && getCapacity() / 2 != 0) {
+      resize((getCapacity() / 2) as int);
     }
     return ret;
   }
 
-  void resize(int newCapacity){
-
-    List? newArr = List.filled(newCapacity+1, false);
-    for(int i = 0 ; i < arr!.length ; i ++){
+  void resize(int newCapacity) {
+    List? newArr = List.filled(newCapacity + 1, false);
+    for (int i = 0; i < arr!.length; i++) {
       newArr[i] = arr![(i + front) % arr!.length];
     }
     arr = newArr;
@@ -48,17 +46,15 @@ class LoopQueue<T> implements Queue<T>{
 
   @override
   void enqueue(e) {
-
-    if((tail + 1) % arr!.length == front)
-      resize(getCapacity() * 2);
+    if ((tail + 1) % arr!.length == front) resize(getCapacity() * 2);
     arr![tail] = e;
     tail = (tail + 1) % arr!.length;
     size++;
   }
 
   @override
   getFront() {
-    if(isEmpty()){
+    if (isEmpty()) {
       throw Exception("Queue is empty.");
     }
     return arr![front];
@@ -71,21 +67,19 @@ class LoopQueue<T> implements Queue<T>{
 
   @override
   bool isEmpty() {
-    return front == tail ;
+    return front == tail;
   }
 
   @override
   String toString() {
     StringBuffer buffer = new StringBuffer();
     buffer.write("Queue: size = $size , capacity = ${getCapacity()} \n");
     buffer.write('front [');
-    for(int i = front ; i != tail ; i = (i + 1) % arr!.length){
+    for (int i = front; i != tail; i = (i + 1) % arr!.length) {
       buffer.write(arr![i]);
-      if((i + 1) % arr!.length != tail)
-        buffer.write(", ");
+      if ((i + 1) % arr!.length != tail) buffer.write(", ");
     }
     buffer.write("] tail");
     return buffer.toString();
   }
-
-}
+}

dart/04-Stack-Queue/Main.dart

@@ -2,7 +2,7 @@ import 'ArrayStack.dart';
 import 'ArrayQueue.dart';
 import 'LoopQueue.dart';
 
-void main(){
+void main() {
 //  ArrayStack<int> stack = new ArrayStack<int>();
 //  for(int i = 0 ; i < 10 ; i ++){
 //    stack.push(i);
@@ -22,13 +22,14 @@ void main(){
 //  }
 
   LoopQueue<int> loopQueue = new LoopQueue<int>();
-  for(int i = 0 ; i < 30 ; i ++){
+
+  for (int i = 0; i < 30; i++) {
     loopQueue.enqueue(i);
     print(loopQueue);
 
-    if(i % 3 == 2){
+    if (i % 3 == 2) {
       loopQueue.dequeue();
       print(loopQueue);
     }
   }
-}
+}

python/loopqueue.py

@@ -0,0 +1,62 @@
+class LoopQueue(object):
+
+    def __init__(self, n=10):
+        self.arr = [None] * (n)  
+        self.front = 0
+        self.tail = 0
+        self.size = 0
+
+    def getCapacity(self):
+        capacity = len(self.arr) - 1;
+        return capacity;
+
+    def dequeue(self):
+        if self.isEmpty() :
+            raise Exception("Cannot dequeue from an empty queue")
+        ret = self.arr[self.front]
+        self.arr[self.front] = None
+        self.front = (self.front + 1)%len(self.arr)
+        self.size -=1
+        if((self.size == self.getCapacity()//4)) and (self.getCapacity()/2 !=0):
+            resize(self.getCapacity()//2)
+        return ret
+
+    def resize(self,newCapacity):
+        newArr = [None]*(newCapacity+1)
+        for i in range(0,len(self.arr)):
+            newArr[i] = self.arr[(i+self.front)%len(self.arr)];
+        self.arr = newArr
+        self.front = 0;
+        self.tail = self.size;
+    
+    def enqueue(self,element):
+        print('当前大小:',self.size)
+        if ((self.tail+1)%len(self.arr)) == self.front:
+            self.resize(self.getCapacity()*2)
+        self.arr[self.tail] = element
+        self.tail = (self.tail +1)% len(self.arr)
+        self.size += 1
+        print('当前大小:',self.size)
+
+    def getFront(self):
+        if(self.isEmpty()):
+            raise Exception("Queue is empty.")        
+        return self.arr[self.front]
+
+    def getSize(self):
+        return len(self.arr)
+    
+    def isEmpty(self):
+        return self.front == self.tail
+        
+    def __str__(self):
+        return "front ["+" ".join(map(str, self.arr)) + "] tail"
+
+if __name__ == '__main__':
+    loopQueue = LoopQueue();
+    for i in range(0,30):
+        loopQueue.enqueue(i);
+        print(loopQueue)
+
+      
+      

python/queue.py

@@ -0,0 +1,44 @@
+'''
+    队列
+'''
+class Queue(object):
+
+    # 初始化 
+    def __init__(self):
+        self.__list = []
+
+    #添加元素
+    def push(self,element):
+        self.__list.append(element)
+
+    # 弹出元素
+    def pop(self):
+       if self.isEmpty():
+           return None
+       else:
+           return self.__list.pop(0)
+
+    #是否为空
+    def isEmpty(self):
+        return len(self.__list) == 0
+    
+    def getSize(self):
+        return len(self.__list)
+    
+    def __str__(self):
+       return " ".join(map(str, self.__list))
+
+if __name__ == '__main__':
+    testQueue = Queue();
+    testQueue.push(1)
+    testQueue.push(2)
+    testQueue.push(3)
+    testQueue.push(4)
+    print(testQueue)  
+    testQueue.pop()
+    print(testQueue)  
+
+
+    
+        
+

python/stack.py

@@ -0,0 +1,44 @@
+'''
+    栈
+'''
+class Stack(object):
+
+    # 初始化 
+    def __init__(self):
+        self.__list = []
+
+    #添加元素
+    def push(self,element):
+        self.__list.append(element)
+
+    # 弹出元素
+    def pop(self):
+       if self.isEmpty():
+           return None
+       else:
+           return self.__list.pop()
+
+    #是否为空
+    def isEmpty(self):
+        return len(self.__list) == 0
+    
+    def getSize(self):
+        return len(self.__list)
+    
+    def __str__(self):
+       return " ".join(map(str, self.__list))
+
+if __name__ == '__main__':
+    testStack = Stack();
+    testStack.push(1)
+    testStack.push(2)
+    testStack.push(3)
+    testStack.push(4)
+    print(testStack)  
+    testStack.pop()
+    print(testStack)  
+
+
+    
+        
+