You cannot select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
116 lines
2.3 KiB
Plaintext
116 lines
2.3 KiB
Plaintext
/* $Id$ */
|
|
|
|
/**
|
|
* Priority Queue.
|
|
* Peek and Pop always return the current lowest value in the list.
|
|
* Sort is done on insertion only.
|
|
*/
|
|
class PriorityQueue
|
|
{
|
|
_queue = null;
|
|
_count = 0;
|
|
|
|
constructor()
|
|
{
|
|
_count = 0;
|
|
_queue = [];
|
|
}
|
|
|
|
/**
|
|
* Insert a new entry in the list.
|
|
* The complexity of this operation is O(n).
|
|
* @param item The item to add to the list.
|
|
* @param priority The priority this item has.
|
|
*/
|
|
function Insert(item, priority);
|
|
|
|
/**
|
|
* Pop the first entry of the list.
|
|
* This is always the item with the lowest priority.
|
|
* The complexity of this operation is O(1).
|
|
* @return The item of the entry with the lowest priority.
|
|
*/
|
|
function Pop();
|
|
|
|
/**
|
|
* Peek the first entry of the list.
|
|
* This is always the item with the lowest priority.
|
|
* The complexity of this operation is O(1).
|
|
* @return The item of the entry with the lowest priority.
|
|
*/
|
|
function Peek();
|
|
|
|
/**
|
|
* Get the amount of current items in the list.
|
|
* The complexity of this operation is O(1).
|
|
* @return The amount of items currently in the list.
|
|
*/
|
|
function Count();
|
|
|
|
/**
|
|
* Check if an item exists in the list.
|
|
* The complexity of this operation is O(n).
|
|
* @param item The item to check for.
|
|
* @return True if the item is already in the list.
|
|
*/
|
|
function Exists(item);
|
|
};
|
|
|
|
function PriorityQueue::Insert(item, priority)
|
|
{
|
|
/* Append dummy entry */
|
|
_queue.append(0);
|
|
_count++;
|
|
|
|
local i;
|
|
/* Find the point of insertion */
|
|
for (i = _count - 2; i >= 0; i--) {
|
|
if (priority > _queue[i][1]) {
|
|
/* All items bigger move one place to the right */
|
|
_queue[i + 1] = _queue[i];
|
|
} else if (item == _queue[i][0]) {
|
|
/* Same item, ignore insertion */
|
|
return false;
|
|
} else {
|
|
/* Found place to insert at */
|
|
break;
|
|
}
|
|
}
|
|
/* Insert new pair */
|
|
_queue[i + 1] = [item, priority];
|
|
|
|
return true;
|
|
}
|
|
|
|
function PriorityQueue::Pop()
|
|
{
|
|
if (_count == 0) return null;
|
|
|
|
local node = _queue.pop();
|
|
_count--;
|
|
|
|
return node[0];
|
|
}
|
|
|
|
function PriorityQueue::Peek()
|
|
{
|
|
if (_count == 0) return null;
|
|
|
|
return _queue[_count - 1][0];
|
|
}
|
|
|
|
function PriorityQueue::Count()
|
|
{
|
|
return _count;
|
|
}
|
|
|
|
function PriorityQueue::Exists(item)
|
|
{
|
|
/* Brute-force find the item (there is no faster way, as we don't have the priority number) */
|
|
foreach (node in _queue) {
|
|
if (node[0] == item) return true;
|
|
}
|
|
|
|
return false;
|
|
}
|