Thread: PriorityQueue Enquiries

Hi All,

I try to google around for how can i do the following thing in priorityqueue but there is no answer for this.

It is actually quite straight forward, lets said i have a set of PriorityQueue with few items inside and I want to get the object n in the pq and do a comparison, if the path is higher cost, replace with a new object n. The Pseudo code is something like this.

If Child.STATE is in PriorityQueue with Higer PATH-COST then
replace that PriorityQueue with the Child.STATE

Anyone able to guide me on this? Coz i believe PriorityQueue does not have the GET function.

Cheers.

Would contains and remove do what you want?

Originally Posted by Norm

Would contains and remove do what you want?

I would like to get the Object N from the priority Queue and do a comparison with current object .. if current object contains lesser cost-path, it will replace the object N..

2 Object would have same attribute different path cost ...

Is it more like a travel using UCS ..

Can you write a small simple program that compiles and executes to show what you want to do?

Originally Posted by Norm

Can you write a small simple program that compiles and executes to show what you want to do?

My program is something like this.

I have an input files as follow

5 5
1 1
5 5

1 1 1 1 1
1 1 1 1 1
1 1 1 1 1
1 1 1 1 1

5 5 = indicates Grid Size
1 1 = indicates Start Location
5 5 = indicates Goal Location
The travel path will be replaced by *

The real answer should be

* 1 1 1 1
* 1 1 2 1
* 1 3 1 1
* 1 1 1 1
* * * * *

It would use priority queue to compare if terrain level is higher or same level using the following formula.

If Node(c,d) - Node(a,b) > 0 then
Path Cost = 1 + Node(c,d)[Terrain Level] - Node(a,b)[Terrain Level] + Parent Path Cost

The start goal will have 0 path cost.

It should travel by 4 direction in sequence, Up - Down - Left - Right

My output files as follow:-

* * * * *
1 1 1 2 *
1 1 3 1 *
1 1 1 1 *
1 1 1 1 *

So, what i suspect my program wrong is because i do not compare the path cost which contain the node.

sorry I meant a java program that compiles and executes to show what you want to do. You know, with classes and methods that execute.

Originally Posted by keat84

I would like to get the Object N from the priority Queue

A queue is a queue - get(int) works on a list. If you want to get the nth item based on a 'cost' you'll have to use Collections.sort on a list (or Arrays.sort on an array) and pass it a Comparator that uses your cost calculation (if it's not already your object's natural order).