问你需要前一个节点指针来实现一个队列吗？

EN

#include <bits/stdc++.h> 
using namespace std; 
  
struct QNode { 
    int data; 
    QNode* next; 
    QNode(int d) 
    { 
        data = d; 
        next = NULL; 
    } 
}; 
  
struct Queue { 
    QNode *front, *rear; 
    Queue() 
    { 
        front = rear = NULL; 
    } 
  
    void enQueue(int x) 
    { 
  
        // Create a new LL node 
        QNode* temp = new QNode(x); 
  
        // If queue is empty, then 
        // new node is front and rear both 
        if (rear == NULL) { 
            front = rear = temp; 
            return; 
        } 
  
        // Add the new node at 
        // the end of queue and change rear 
        rear->next = temp; 
        rear = temp; 
    } 
  
    // Function to remove 
    // a key from given queue q 
    void deQueue() 
    { 
        // If queue is empty, return NULL. 
        if (front == NULL) 
            return; 
  
        // Store previous front and 
        // move front one node ahead 
        QNode* temp = front; 
        front = front->next; 
  
        // If front becomes NULL, then 
        // change rear also as NULL 
        if (front == NULL) 
            rear = NULL; 
  
        delete (temp); 
    } 
}; 
  
// Driven Program 
int main() 
{ 
  
    Queue q; 
    q.enQueue(10); 
    q.enQueue(20); 
    q.deQueue(); 
    q.deQueue(); 
    q.enQueue(30); 
    q.enQueue(40); 
    q.enQueue(50); 
    q.deQueue(); 
    cout << "Queue Front : " << (q.front)->data << endl; 
    cout << "Queue Rear : " << (q.rear)->data; 
} 
// This code is contributed by rathbhupendra