Several enhancements and fixes

codes/cpp/chapter_stack_and_queue/array_queue.cpp

@@ -37,7 +37,7 @@ class ArrayQueue {
     }
 
     /* 判断队列是否为空 */
-    bool empty() {
+    bool isEmpty() {
         return size() == 0;
     }
 
@@ -65,7 +65,7 @@ class ArrayQueue {
 
     /* 访问队首元素 */
     int peek() {
-        if (empty())
+        if (isEmpty())
             throw out_of_range("队列为空");
         return nums[front];
     }
@@ -110,7 +110,7 @@ int main() {
     cout << "队列长度 size = " << size << endl;
 
     /* 判断队列是否为空 */
-    bool empty = queue->empty();
+    bool empty = queue->isEmpty();
     cout << "队列是否为空 = " << empty << endl;
 
     /* 测试环形数组 */

codes/cpp/chapter_stack_and_queue/array_stack.cpp

@@ -18,8 +18,8 @@ class ArrayStack {
     }
 
     /* 判断栈是否为空 */
-    bool empty() {
-        return stack.empty();
+    bool isEmpty() {
+        return stack.size() == 0;
     }
 
     /* 入栈 */
@@ -35,7 +35,7 @@ class ArrayStack {
 
     /* 访问栈顶元素 */
     int top() {
-        if (empty())
+        if (isEmpty())
             throw out_of_range("栈为空");
         return stack.back();
     }
@@ -74,7 +74,7 @@ int main() {
     cout << "栈的长度 size = " << size << endl;
 
     /* 判断是否为空 */
-    bool empty = stack->empty();
+    bool empty = stack->isEmpty();
     cout << "栈是否为空 = " << empty << endl;
 
     // 释放内存

codes/cpp/chapter_stack_and_queue/linkedlist_deque.cpp

@@ -81,9 +81,8 @@ class LinkedListDeque {
 
     /* 出队操作 */
     int pop(bool isFront) {
-        // 若队列为空，直接返回 -1
         if (isEmpty())
-            return -1;
+            throw out_of_range("队列为空");
         int val;
         // 队首出队操作
         if (isFront) {
@@ -124,12 +123,16 @@ class LinkedListDeque {
 
     /* 访问队首元素 */
     int peekFirst() {
-        return isEmpty() ? -1 : front->val;
+        if (isEmpty())
+            throw out_of_range("双向队列为空");
+        return front->val;
     }
 
     /* 访问队尾元素 */
     int peekLast() {
-        return isEmpty() ? -1 : rear->val;
+        if (isEmpty())
+            throw out_of_range("双向队列为空");
+        return rear->val;
     }
 
     /* 返回数组用于打印 */

codes/cpp/chapter_stack_and_queue/linkedlist_queue.cpp

@@ -30,7 +30,7 @@ class LinkedListQueue {
     }
 
     /* 判断队列是否为空 */
-    bool empty() {
+    bool isEmpty() {
         return queSize == 0;
     }
 
@@ -109,7 +109,7 @@ int main() {
     cout << "队列长度 size = " << size << endl;
 
     /* 判断队列是否为空 */
-    bool empty = queue->empty();
+    bool empty = queue->isEmpty();
     cout << "队列是否为空 = " << empty << endl;
 
     // 释放内存

codes/cpp/chapter_stack_and_queue/linkedlist_stack.cpp

@@ -29,7 +29,7 @@ class LinkedListStack {
     }
 
     /* 判断栈是否为空 */
-    bool empty() {
+    bool isEmpty() {
         return size() == 0;
     }
 
@@ -53,7 +53,7 @@ class LinkedListStack {
 
     /* 访问栈顶元素 */
     int top() {
-        if (size() == 0)
+        if (isEmpty())
             throw out_of_range("栈为空");
         return stackTop->val;
     }
@@ -98,7 +98,7 @@ int main() {
     cout << "栈的长度 size = " << size << endl;
 
     /* 判断是否为空 */
-    bool empty = stack->empty();
+    bool empty = stack->isEmpty();
     cout << "栈是否为空 = " << empty << endl;
 
     // 释放内存