假设循环队列数组长度为 N=7，队空判断条件为 front==rear。依次执行入队和出队操作后，最终 (front, rear) 的值是

N = 7
q = [0] * N
front = 3
rear = 3

def enqueue(x):
    global rear
    q[rear] = x
    rear = (rear + 1) % N

def dequeue():
    global front
    front = (front + 1) % N

enqueue(10)
enqueue(20)
enqueue(30)
dequeue()
enqueue(40)
dequeue()
enqueue(50)