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POIterate over an ArrayList containing ArrayList
 

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    <p>I am working on a bagging problem. I am given a list of items(ints), and bags that have a maxSize. I am trying to find the least possible amount of bags to fit all the items. I need to do this in a recursive method. </p> <p>I am storing bag objects (That are ArrayList of integers, with some helper methods of checking if the size + an int will be greater than the maxSize of the bag). I am then storing all of these bags in an ArrayList objects. The problem I am running into is I seem to be adding every item to every bag. Below is the method I believe the problem is. I can't think of a way to exit once I have found I can add the item to the bag at 'i'. At this point I need to get a new item, and try to bag it at the first bag, if it doesn't fit then try the second, third etc. </p> <p>baggedList = ArrayList :::: recList = List of ints I am trying to bag </p> <p>I feel like I am over complicating this. If you have any better suggestions please do tell. </p> <pre><code> public boolean bagging (ArrayList&lt;Integer&gt; recList){ boolean keepBagging = true; System.out.println("right before the recursive method"); System.out.println("the reclist before while loop" + recList.toString()); while (!recList.isEmpty() &amp;&amp; keepBagging){ int item = recList.remove(recList.size() -1); for (int i= 0; i &lt; baggedList.size(); i ++){ System.out.println("i = " + i + " Item = " + item); if (tryToBag(item, i)){ //boolean method addItem (item, i); //adds the item bagging (recList); //recursive call } else { System.out.println("FAILED" + keepBagging); keepBagging = false; } } } return keepBagging; } </code></pre> <p>CanBag method that calls a Bag method</p> <pre><code> private boolean tryToBag(int item, int i) { boolean canBag = false; Bag currentBag = baggedList.get(i); ArrayList&lt;Integer&gt; list = currentBag.getList(); if (currentBag.canBag(item)){ canBag = true; } return canBag; } </code></pre> <p>canBag method </p> <pre><code> public boolean canBag(int size){ if (size + Bag.sum() &lt;= maxBagSize){ return true; } else return false; } </code></pre> <p>toString</p> <pre><code> public String toString(){ int counter = 0; String ret = ""; for (int i = 0; i &lt; baggedList.size(); i++){ Bag tryThisBag = baggedList.get(i); ret += "bag " + counter + tryThisBag.getList().toString(); counter++; } return ret; } </code></pre> <p>addItem method</p> <pre><code> private void addItem(int item, int i) { Bag currentBag = baggedList.remove(i); //removing list ArrayList&lt;Integer&gt; list = currentBag.getList(); // new list list.add(item); //adding item System.out.println ("List here at bag" + i + " : " + list.toString()); currentBag.setList(list); // sets the arrayList back to the bag object baggedList.add(i, currentBag); //sets the bag at the index in the collection of bags } </code></pre>
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    1. COCan you tell declaration of this baggedList .. which.size() u checking in for loop..! also what addItem() do..add in what ?
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      1. USNeha
    2. COArrayList<Bag> baggedList. Is the declaration. A 'Bag' is just an ArrayList<Integer>. The size() is the amount of 'Bags' I can use. I have initialized it before this method. I am given the amount of available bags. AddItem() takes the 'Bag' out of baggedList by index, and just adds it to that 'Bag' ArrayList.
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    3. COQuoting from your question "I am then storing all of these bags in an ArrayList objects." Can't you store these bag objects in a TreeMap with maxsize being a key. Hence the <K,V> with maxsize 1 will have bag that can accommodate values less than or equal to 1. The bag with size 2 can values less than or equal to 2.
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      1. USAnupam Saini
 

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