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POKeeping largest 10 numbers
 

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  1. POKeeping largest 10 numbers
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    <p>While iterating through a dataset, what's the best way to keep track of only the top 10 numbers so far, in sorted order?</p> <p>Solution...Ended up implementing Generic Min and Max Heaps...as sadly they are not available in Java libraries or readily on the internet....No gauruntees on the code...</p> <pre><code>import java.util.ArrayList; public class MaxHeapGeneric &lt;K extends Comparable&gt; { //ArrayList to hold the heap ArrayList&lt;K&gt; h = new ArrayList&lt;K&gt;(); public MaxHeapGeneric() { } public int getSize() { return h.size(); } private K get(int key){ return h.get(key); } public void add(K key){ h.add(null); int k = h.size() - 1; while (k &gt; 0){ int parent = (k-1)/2; K parentValue = h.get(parent); //MaxHeap - //for minheap - if(key &gt; parentValue) if(key.compareTo(parentValue) &lt;= 0) break; h.set(k, parentValue); k = parent; } h.set(k, key); } public K getMax() { return h.get(0); } public void percolateUp(int k, K key){ if(h.isEmpty()) return ; while(k &lt; h.size() /2){ int child = 2*k + 1; //left child if( child &lt; h.size() -1 &amp;&amp; (h.get(child).compareTo(h.get(child+1)) &lt; 0) ) { child++; } if(key.compareTo(h.get(child)) &gt;=0) break; h.set(k, h.get(child)); k = child; } h.set(k, key); } public K remove() { K removeNode = h.get(0); K lastNode = h.remove(h.size() - 1); percolateUp(0, lastNode); return removeNode; } public boolean isEmpty() { return h.isEmpty(); } public static void main(String[] args) { MaxHeapGeneric&lt;Integer&gt; test = new MaxHeapGeneric&lt;Integer&gt;(); test.add(5); test.add(9); test.add(445); test.add(1); test.add(534); test.add(23); while(!test.isEmpty()) { System.out.println(test.remove()); } } } </code></pre> <p>And a min heap</p> <pre><code>import java.util.ArrayList; public class MinHeapGeneric &lt;K extends Comparable&gt; { //ArrayList to hold the heap ArrayList&lt;K&gt; h = new ArrayList&lt;K&gt;(); public MinHeapGeneric() { } public int getSize() { return h.size(); } private K get(int key){ return h.get(key); } public void add(K key){ h.add(null); int k = h.size() - 1; while (k &gt; 0){ int parent = (k-1)/2; K parentValue = h.get(parent); //for minheap - if(key &gt; parentValue) if(key.compareTo(parentValue) &gt; 0) break; h.set(k, parentValue); k = parent; } h.set(k, key); } public K getMax() { return h.get(0); } public void percolateUp(int k, K key){ if(h.isEmpty()) return ; while(k &lt; h.size() /2){ int child = 2*k + 1; //left child if( child &lt; h.size() -1 &amp;&amp; (h.get(child).compareTo(h.get(child+1)) &gt;= 0) ) { child++; } if(key.compareTo(h.get(child)) &lt; 0) break; h.set(k, h.get(child)); k = child; } h.set(k, key); } public K remove() { K removeNode = h.get(0); K lastNode = h.remove(h.size() - 1); percolateUp(0, lastNode); return removeNode; } public boolean isEmpty() { return h.isEmpty(); } public static void main(String[] args) { MinHeapGeneric&lt;Integer&gt; test = new MinHeapGeneric&lt;Integer&gt;(); test.add(5); test.add(9); test.add(445); test.add(1); test.add(534); test.add(23); while(!test.isEmpty()) { System.out.println(test.remove()); } } } </code></pre>
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    1. PTQuestion
    1. USuser623879
    1. USuser623879
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    1. COHeap sort or link list.
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      1. USiamsleepy
    2. COLinked list or array.
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      1. USFoo Bah
 

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