下面 search 函数的平均时间复杂度为(     )。

int search(int n, int * p, int target) {

int low = 0, high = n;

while (low <= high) {

int middle = (low + high) / 2;

if (target == p[middle]) {

return middle;

} else if (target > p[middle]) {

low = middle + 1;

} else {

high = middle - 1;

}

}

return -1;

}