【LeetCode刷题日记】[641. 设计循环双端队列]

【LeetCode刷题日记】641. 设计循环双端队列

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。

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C++

#include <iostream>
#include <vector>

using namespace std;

class MyCircularDeque {

private:
    vector<int> arr;
    int front;
    int rear;
    int capacity;

public:
    /** Initialize your data structure here. Set the size of the deque to be k. */
    MyCircularDeque(int k) {
        capacity = k + 1;
        arr.assign(capacity, 0);

        front = 0;
        rear = 0;
    }

    /** Adds an item at the front of Deque. Return true if the operation is successful. */
    bool insertFront(int value) {
        if (isFull()) {
            return false;
        }
        front = (front - 1 + capacity) % capacity;
        arr[front] = value;
        return true;
    }

    /** Adds an item at the rear of Deque. Return true if the operation is successful. */
    bool insertLast(int value) {
        if (isFull()) {
            return false;
        }
        arr[rear] = value;
        rear = (rear + 1) % capacity;
        return true;
    }

    /** Deletes an item from the front of Deque. Return true if the operation is successful. */
    bool deleteFront() {
        if (isEmpty()) {
            return false;
        }
        // front 被设计在数组的开头，所以是 +1
        front = (front + 1) % capacity;
        return true;
    }

    /** Deletes an item from the rear of Deque. Return true if the operation is successful. */
    bool deleteLast() {
        if (isEmpty()) {
            return false;
        }
        // rear 被设计在数组的末尾，所以是 -1
        rear = (rear - 1 + capacity) % capacity;
        return true;
    }

    /** Get the front item from the deque. */
    int getFront() {
        if (isEmpty()) {
            return -1;
        }
        return arr[front];
    }

    /** Get the last item from the deque. */
    int getRear() {
        if (isEmpty()) {
            return -1;
        }
        // 当 rear 为 0 时防止数组越界
        return arr[(rear - 1 + capacity) % capacity];
    }

    /** Checks whether the circular deque is empty or not. */
    bool isEmpty() {
        return front == rear;
    }

    /** Checks whether the circular deque is full or not. */
    bool isFull() {
        // 注意：这个设计是非常经典的做法
        return (rear + 1) % capacity == front;
    }
};

/**
 * Your MyCircularDeque object will be instantiated and called as such:
 * MyCircularDeque* obj = new MyCircularDeque(k);
 * bool param_1 = obj->insertFront(value);
 * bool param_2 = obj->insertLast(value);
 * bool param_3 = obj->deleteFront();
 * bool param_4 = obj->deleteLast();
 * int param_5 = obj->getFront();
 * int param_6 = obj->getRear();
 * bool param_7 = obj->isEmpty();
 * bool param_8 = obj->isFull();
 */

C

typedef struct NODE{
    int val;
    struct NODE* pre;
    struct NODE* next;
} MyNode;

typedef struct {
    int size;
    int cursize;
    MyNode* head;
    MyNode* tail;
} MyCircularDeque;


/** Initialize your data structure here. Set the size of the deque to be k. */

MyCircularDeque* myCircularDequeCreate(int k) {
    MyCircularDeque* MyDeque = calloc(k, sizeof(MyCircularDeque));
    MyDeque->head = NULL;
    MyDeque->tail = NULL;
    MyDeque->size = k;
    MyDeque->cursize = 0;
    return MyDeque;
}

/** Adds an item at the front of Deque. Return true if the operation is successful. */
bool myCircularDequeInsertFront(MyCircularDeque* obj, int value) {
    if (obj->size == obj->cursize) {
        return false;
    }
    MyNode* node = calloc(1,sizeof(MyNode));
    node->val = value;
    if (obj->head == NULL) {
        obj->head = node;
        obj->tail = node;
    } else {
        obj->head->pre = node;
        node->next = obj->head;
        node->pre = NULL;
        obj->head = node;
    }
    obj->cursize++;
    return true;
}

/** Adds an item at the rear of Deque. Return true if the operation is successful. */
bool myCircularDequeInsertLast(MyCircularDeque* obj, int value) {
    if (obj->size == obj->cursize) {
        return false;
    }
    MyNode* node = calloc(1,sizeof(MyNode));
    node->val = value;
    if (obj->head == NULL) {
        obj->head = node;
        obj->tail = node;
    } else {
        node->next = NULL;
        obj->tail->next = node;
        node->pre = obj->tail;
        node->next = NULL;
        obj->tail = node;
    }
    obj->cursize++;
    return true;
}

/** Deletes an item from the front of Deque. Return true if the operation is successful. */
bool myCircularDequeDeleteFront(MyCircularDeque* obj) {
    if (obj->cursize == 0) {
        return false;
    }
    if (obj->cursize == 1) {
        free(obj->head);
        obj->head = NULL;
        obj->tail = NULL;
    } else {
        MyNode* temp = obj->head;
        obj->head = temp->next;
        obj->head->pre = NULL;
        free(temp);
    }
    obj->cursize--;
    return true;
}

/** Deletes an item from the rear of Deque. Return true if the operation is successful. */
bool myCircularDequeDeleteLast(MyCircularDeque* obj) {
    if (obj->cursize == 0) {
        return false;
    }
    if (obj->cursize == 1) {
        free(obj->head);
        obj->head = NULL;
        obj->tail = NULL;
    } else {
        MyNode* temp = obj->tail;
        obj->tail = temp->pre;
        obj->tail->next = NULL;
        free(temp);
    }
    obj->cursize--;
    return true;
}

/** Get the front item from the deque. */
int myCircularDequeGetFront(MyCircularDeque* obj) {
    if (obj->cursize == 0) {
        return -1;
    }
    return obj->head->val;
}

/** Get the last item from the deque. */
int myCircularDequeGetRear(MyCircularDeque* obj) {
    if (obj->cursize == 0) {
        return -1;
    }
    return obj->tail->val;
}

/** Checks whether the circular deque is empty or not. */
bool myCircularDequeIsEmpty(MyCircularDeque* obj) {
    if (obj->cursize == 0) {
        return true;
    }
    return false;
}

/** Checks whether the circular deque is full or not. */
bool myCircularDequeIsFull(MyCircularDeque* obj) {
    if (obj->size == obj->cursize) {
        return true;
    }
    return false;
}

void myCircularDequeFree(MyCircularDeque* obj) {
    if (obj == NULL) {
        return ;
    }
    MyNode* temp = obj->head;
    while (temp) {
        MyNode* temp1 = temp;
        temp = temp->next;
        free(temp1);
    }
    free(obj);
    obj = NULL;
}

/**
 * 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);
*/