A circular queue is stored in A[0,1,⋯,n−1] ,its head and tail pointer are f,r.How many elements does the queue have?
时间: 2024-03-14 20:47:35 浏览: 156
If a circular queue is stored in A[0, 1, ⋯, n−1] and its head and tail pointers are f and r respectively, the number of elements in the queue can be calculated using the following formula:
```
number of elements = (r - f + n) % n
```
Here, `%` is the modulo operator. The expression `(r - f + n)` calculates the number of positions between the head and tail pointers, including the positions that wrap around to the beginning of the array due to the circular nature of the queue. Taking the modulus with `n` ensures that the result is always between 0 and `n-1` inclusive.
For example, consider a circular queue with `n=5`, `f=1`, and `r=4`. The number of elements in the queue is:
```
number of elements = (r - f + n) % n
= (4 - 1 + 5) % 5
= 8 % 5
= 3
```
Therefore, the circular queue has 3 elements.
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