LeetCode:641. Design Circular Deque设计循环双端队列（C语言）

秒速五厘米 2022-12-31 05:17 119阅读 0赞

**题目描述：**  
设计实现双端队列。  
你的实现需要支持以下操作：

MyCircularDeque(k)：构造函数,双端队列的大小为k。
    insertFront()：将一个元素添加到双端队列头部。 如果操作成功返回 true。
    insertLast()：将一个元素添加到双端队列尾部。如果操作成功返回 true。
    deleteFront()：从双端队列头部删除一个元素。 如果操作成功返回 true。
    deleteLast()：从双端队列尾部删除一个元素。如果操作成功返回 true。
    getFront()：从双端队列头部获得一个元素。如果双端队列为空，返回 -1。
    getRear()：获得双端队列的最后一个元素。 如果双端队列为空，返回 -1。
    isEmpty()：检查双端队列是否为空。
    isFull()：检查双端队列是否满了。

示例：

MyCircularDeque circularDeque = new MycircularDeque(3); // 设置容量大小为3  
circularDeque.insertLast(1); // 返回 true  
circularDeque.insertLast(2); // 返回 true  
circularDeque.insertFront(3); // 返回 true  
circularDeque.insertFront(4); // 已经满了，返回 false  
circularDeque.getRear(); // 返回 2  
circularDeque.isFull(); // 返回 true  
circularDeque.deleteLast(); // 返回 true  
circularDeque.insertFront(4); // 返回 true  
circularDeque.getFront(); // 返回 4

提示：

所有值的范围为 [1, 1000]
    操作次数的范围为 [1, 1000]
    请不要使用内置的双端队列库。

来源：力扣（LeetCode）  
链接：https://leetcode-cn.com/problems/design-circular-deque  
著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。  
**解答：**

typedef struct { 
    	int *arr;
    	int head;
    	int tail;
    	int size;
    
    } MyCircularDeque;
    bool myCircularDequeIsFull(MyCircularDeque* obj) ;
    bool myCircularDequeIsEmpty(MyCircularDeque* obj) ;
    /** Initialize your data structure here. Set the size of the deque to be k. */
    
    MyCircularDeque* myCircularDequeCreate(int k) { 
    
    	MyCircularDeque *obj = malloc(sizeof(MyCircularDeque) * (k+1));
    	obj->arr = malloc(sizeof(int) * (k+1));
    	obj->head = 0;
    	obj->tail = 0;
    	obj->size = k + 1;
    	return obj;
    
    }
    
    /** Adds an item at the front of Deque. Return true if the operation is successful. */
    bool myCircularDequeInsertFront(MyCircularDeque* obj, int value) { 
    
    	if ( myCircularDequeIsFull(obj)) return false;
    
    	int pos = (obj->head+obj->size-1) % obj->size;
    	obj->arr[pos] = value;
    	obj->head = pos;
    	return true;
    
    
    }
    
    /** Adds an item at the rear of Deque. Return true if the operation is successful. */
    bool myCircularDequeInsertLast(MyCircularDeque* obj, int value) { 
    	if ( myCircularDequeIsFull(obj)) return false;
    
    	obj->arr[obj->tail] = value;
    	obj->tail = (obj->tail+1) % obj->size;
    
    	return true;
    
    }
    
    /** Deletes an item from the front of Deque. Return true if the operation is successful. */
    bool myCircularDequeDeleteFront(MyCircularDeque* obj) { 
    	if ( myCircularDequeIsEmpty(obj)) return false;
    
    	obj->head = (obj->head+1) % obj->size;
    	return true;
    
    }
    
    /** Deletes an item from the rear of Deque. Return true if the operation is successful. */
    bool myCircularDequeDeleteLast(MyCircularDeque* obj) { 
    	if ( myCircularDequeIsEmpty(obj)) return false;
    
    	obj->tail = (obj->tail-1+obj->size) % obj->size;
    	return true;
    }
    
    /** Get the front item from the deque. */
    int myCircularDequeGetFront(MyCircularDeque* obj) { 
    	if ( myCircularDequeIsEmpty(obj) ) return -1;
    
    	return obj->arr[obj->head];
    
    }
    
    /** Get the last item from the deque. */
    int myCircularDequeGetRear(MyCircularDeque* obj) { 
    	if ( myCircularDequeIsEmpty(obj) ) return -1;
    
    	int pos = (obj->tail+obj->size-1) % obj->size;
    
    	return obj->arr[pos];
    }
    
    /** Checks whether the circular deque is empty or not. */
    bool myCircularDequeIsEmpty(MyCircularDeque* obj) { 
    
    	return (obj->head == obj->tail) ? true : false;
    
    }
    
    /** Checks whether the circular deque is full or not. */
    bool myCircularDequeIsFull(MyCircularDeque* obj) { 
    
    	return (obj->head == (obj->tail+1) % obj->size) ? true : false;
    
    }
    
    void myCircularDequeFree(MyCircularDeque* obj) { 
    	free(obj->arr);
    	free(obj);
    	return ;
    
    }
    
    /** * Your MyCircularDeque struct will be instantiated and called as such: * MyCircularDeque* obj = myCircularDequeCreate(k); * bool param_1 = myCircularDequeInsertFront(obj, value); * bool param_2 = myCircularDequeInsertLast(obj, value); * bool param_3 = myCircularDequeDeleteFront(obj); * bool param_4 = myCircularDequeDeleteLast(obj); * int param_5 = myCircularDequeGetFront(obj); * int param_6 = myCircularDequeGetRear(obj); * bool param_7 = myCircularDequeIsEmpty(obj); * bool param_8 = myCircularDequeIsFull(obj); * myCircularDequeFree(obj); */

**运行结果：**  
![在这里插入图片描述][20201228153624833.png_pic_center]

**Notes：**  
参考官方文档：[https://leetcode-cn.com/problems/design-circular-deque/solution/cyu-yan-shi-xian-40ms-by-xu-zhou-geng/][https_leetcode-cn.com_problems_design-circular-deque_solution_cyu-yan-shi-xian-40ms-by-xu-zhou-geng]

[20201228153624833.png_pic_center]: /images/20221120/dc2c2de921ee48f5b4950a69d1095e1c.png
[https_leetcode-cn.com_problems_design-circular-deque_solution_cyu-yan-shi-xian-40ms-by-xu-zhou-geng]: https://leetcode-cn.com/problems/design-circular-deque/solution/cyu-yan-shi-xian-40ms-by-xu-zhou-geng/