c++ - Dequeue in a priority queue -

i have implemented priority queue array (school work), , looks below:

int dequeue(int a[], int n){      int i, numbertodequeue;     numbertodequeue = a[0];      for(i = 0; < n; i++){         a[i] = a[i+1];     }     return numbertodequeue; } 

dequeue in priority queue should take o(1) time.

however, in code, takes o(1) time dequeue ,

o(n) time shift elements front 1 index.

i wondering if there's better solution has time complexity of o(1).

all form of reply appreciated.

int dequeue(int a[], int n){ //provided numbers in ascending order      int numbertodequeue;     numbertodequeue = a[n - 1];     n--;     return numbertodequeue; }