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<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
<meta name="GENERATOR" content="GNU source-highlight
by Lorenzo Bettini
http://www.lorenzobettini.it
http://www.gnu.org/software/src-highlite">
<title>binary_heap.cpp</title>
</head>
<body style="background-color:white">
<pre><i><span style="color:#9A1900">// Code written by Aaron Bloomfield, 2014</span></i>
<i><span style="color:#9A1900">// Released under a CC BY-SA license</span></i>
<i><span style="color:#9A1900">// This code is part of the https://github.com/aaronbloomfield/pdr repository</span></i>
<b><span style="color:#000080">#include</span></b> <span style="color:#FF0000"><iostream></span>
<b><span style="color:#000080">#include</span></b> <span style="color:#FF0000">"binary_heap.h"</span>
<b><span style="color:#0000FF">using</span></b> <b><span style="color:#0000FF">namespace</span></b> std<span style="color:#990000">;</span>
<i><span style="color:#9A1900">// default constructor</span></i>
binary_heap<span style="color:#990000">::</span><b><span style="color:#000000">binary_heap</span></b><span style="color:#990000">()</span> <span style="color:#990000">:</span> <b><span style="color:#000000">heap_size</span></b><span style="color:#990000">(</span><span style="color:#993399">0</span><span style="color:#990000">)</span> <span style="color:#FF0000">{</span>
heap<span style="color:#990000">.</span><b><span style="color:#000000">push_back</span></b><span style="color:#990000">(</span><span style="color:#993399">0</span><span style="color:#990000">);</span>
<span style="color:#FF0000">}</span>
<i><span style="color:#9A1900">// builds a heap from an unsorted vector</span></i>
binary_heap<span style="color:#990000">::</span><b><span style="color:#000000">binary_heap</span></b><span style="color:#990000">(</span><span style="color:#008080">vector<int></span> vec<span style="color:#990000">)</span> <span style="color:#990000">:</span> <b><span style="color:#000000">heap_size</span></b><span style="color:#990000">(</span>vec<span style="color:#990000">.</span><b><span style="color:#000000">size</span></b><span style="color:#990000">())</span> <span style="color:#FF0000">{</span>
heap <span style="color:#990000">=</span> vec<span style="color:#990000">;</span>
heap<span style="color:#990000">.</span><b><span style="color:#000000">push_back</span></b><span style="color:#990000">(</span>heap<span style="color:#990000">[</span><span style="color:#993399">0</span><span style="color:#990000">]);</span>
heap<span style="color:#990000">[</span><span style="color:#993399">0</span><span style="color:#990000">]</span> <span style="color:#990000">=</span> <span style="color:#993399">0</span><span style="color:#990000">;</span>
<b><span style="color:#0000FF">for</span></b> <span style="color:#990000">(</span><span style="color:#009900">int</span> i <span style="color:#990000">=</span> heap_size<span style="color:#990000">/</span><span style="color:#993399">2</span><span style="color:#990000">;</span> i <span style="color:#990000">></span> <span style="color:#993399">0</span><span style="color:#990000">;</span> i<span style="color:#990000">--)</span> <span style="color:#FF0000">{</span>
<b><span style="color:#000000">percolateDown</span></b><span style="color:#990000">(</span>i<span style="color:#990000">);</span>
<span style="color:#FF0000">}</span>
<span style="color:#FF0000">}</span>
<i><span style="color:#9A1900">// the destructor doesn't need to do much</span></i>
binary_heap<span style="color:#990000">::~</span><b><span style="color:#000000">binary_heap</span></b><span style="color:#990000">()</span> <span style="color:#FF0000">{</span>
<span style="color:#FF0000">}</span>
<span style="color:#009900">void</span> binary_heap<span style="color:#990000">::</span><b><span style="color:#000000">insert</span></b><span style="color:#990000">(</span><span style="color:#009900">int</span> x<span style="color:#990000">)</span> <span style="color:#FF0000">{</span>
<i><span style="color:#9A1900">// a vector push_back will resize as necessary</span></i>
heap<span style="color:#990000">.</span><b><span style="color:#000000">push_back</span></b><span style="color:#990000">(</span>x<span style="color:#990000">);</span>
<i><span style="color:#9A1900">// move it up into the right position</span></i>
<b><span style="color:#000000">percolateUp</span></b><span style="color:#990000">(++</span>heap_size<span style="color:#990000">);</span>
<span style="color:#FF0000">}</span>
<span style="color:#009900">void</span> binary_heap<span style="color:#990000">::</span><b><span style="color:#000000">percolateUp</span></b><span style="color:#990000">(</span><span style="color:#009900">int</span> hole<span style="color:#990000">)</span> <span style="color:#FF0000">{</span>
<i><span style="color:#9A1900">// get the value just inserted</span></i>
<span style="color:#009900">int</span> x <span style="color:#990000">=</span> heap<span style="color:#990000">[</span>hole<span style="color:#990000">];</span>
<i><span style="color:#9A1900">// while we haven't run off the top and while the</span></i>
<i><span style="color:#9A1900">// value is less than the parent...</span></i>
<b><span style="color:#0000FF">for</span></b> <span style="color:#990000">(</span> <span style="color:#990000">;</span> <span style="color:#990000">(</span>hole <span style="color:#990000">></span> <span style="color:#993399">1</span><span style="color:#990000">)</span> <span style="color:#990000">&&</span> <span style="color:#990000">(</span>x <span style="color:#990000"><</span> heap<span style="color:#990000">[</span>hole<span style="color:#990000">/</span><span style="color:#993399">2</span><span style="color:#990000">]);</span> hole <span style="color:#990000">/=</span> <span style="color:#993399">2</span><span style="color:#990000">)</span> <span style="color:#FF0000">{</span>
heap<span style="color:#990000">[</span>hole<span style="color:#990000">]</span> <span style="color:#990000">=</span> heap<span style="color:#990000">[</span>hole<span style="color:#990000">/</span><span style="color:#993399">2</span><span style="color:#990000">];</span> <i><span style="color:#9A1900">// move the parent down</span></i>
<span style="color:#FF0000">}</span>
<i><span style="color:#9A1900">// correct position found! insert at that spot</span></i>
heap<span style="color:#990000">[</span>hole<span style="color:#990000">]</span> <span style="color:#990000">=</span> x<span style="color:#990000">;</span>
<span style="color:#FF0000">}</span>
<span style="color:#009900">int</span> binary_heap<span style="color:#990000">::</span><b><span style="color:#000000">deleteMin</span></b><span style="color:#990000">()</span> <span style="color:#FF0000">{</span>
<i><span style="color:#9A1900">// make sure the heap is not empty</span></i>
<b><span style="color:#0000FF">if</span></b> <span style="color:#990000">(</span>heap_size <span style="color:#990000">==</span> <span style="color:#993399">0</span><span style="color:#990000">)</span> <span style="color:#FF0000">{</span>
<b><span style="color:#0000FF">throw</span></b> <span style="color:#FF0000">"deleteMin() called on empty heap"</span><span style="color:#990000">;</span>
<span style="color:#FF0000">}</span>
<i><span style="color:#9A1900">// save the value to be returned</span></i>
<span style="color:#009900">int</span> ret <span style="color:#990000">=</span> heap<span style="color:#990000">[</span><span style="color:#993399">1</span><span style="color:#990000">];</span>
<i><span style="color:#9A1900">// move the last inserted position into the root</span></i>
heap<span style="color:#990000">[</span><span style="color:#993399">1</span><span style="color:#990000">]</span> <span style="color:#990000">=</span> heap<span style="color:#990000">[</span>heap_size<span style="color:#990000">--];</span>
<i><span style="color:#9A1900">// make sure the vector knows that there is one less element</span></i>
heap<span style="color:#990000">.</span><b><span style="color:#000000">pop_back</span></b><span style="color:#990000">();</span>
<i><span style="color:#9A1900">// percolate the root down to the proper position</span></i>
<b><span style="color:#0000FF">if</span></b> <span style="color:#990000">(!</span><b><span style="color:#000000">isEmpty</span></b><span style="color:#990000">())</span> <span style="color:#FF0000">{</span>
<b><span style="color:#000000">percolateDown</span></b><span style="color:#990000">(</span><span style="color:#993399">1</span><span style="color:#990000">);</span>
<span style="color:#FF0000">}</span>
<i><span style="color:#9A1900">// return the old root node</span></i>
<b><span style="color:#0000FF">return</span></b> ret<span style="color:#990000">;</span>
<span style="color:#FF0000">}</span>
<span style="color:#009900">void</span> binary_heap<span style="color:#990000">::</span><b><span style="color:#000000">percolateDown</span></b><span style="color:#990000">(</span><span style="color:#009900">int</span> hole<span style="color:#990000">)</span> <span style="color:#FF0000">{</span>
<i><span style="color:#9A1900">// get the value to percolate down</span></i>
<span style="color:#009900">int</span> x <span style="color:#990000">=</span> heap<span style="color:#990000">[</span>hole<span style="color:#990000">];</span>
<i><span style="color:#9A1900">// while there is a left child...</span></i>
<b><span style="color:#0000FF">while</span></b> <span style="color:#990000">(</span>hole<span style="color:#990000">*</span><span style="color:#993399">2</span> <span style="color:#990000"><=</span> heap_size<span style="color:#990000">)</span> <span style="color:#FF0000">{</span>
<span style="color:#009900">int</span> child <span style="color:#990000">=</span> hole<span style="color:#990000">*</span><span style="color:#993399">2</span><span style="color:#990000">;</span> <i><span style="color:#9A1900">// the left child</span></i>
<i><span style="color:#9A1900">// is there a right child? if so, is it lesser?</span></i>
<b><span style="color:#0000FF">if</span></b> <span style="color:#990000">((</span>child<span style="color:#990000">+</span><span style="color:#993399">1</span> <span style="color:#990000"><=</span> heap_size<span style="color:#990000">)</span> <span style="color:#990000">&&</span> <span style="color:#990000">(</span>heap<span style="color:#990000">[</span>child<span style="color:#990000">+</span><span style="color:#993399">1</span><span style="color:#990000">]</span> <span style="color:#990000"><</span> heap<span style="color:#990000">[</span>child<span style="color:#990000">]))</span> <span style="color:#FF0000">{</span>
child<span style="color:#990000">++;</span>
<span style="color:#FF0000">}</span>
<i><span style="color:#9A1900">// if the child is greater than the node...</span></i>
<b><span style="color:#0000FF">if</span></b> <span style="color:#990000">(</span>x <span style="color:#990000">></span> heap<span style="color:#990000">[</span>child<span style="color:#990000">])</span> <span style="color:#FF0000">{</span>
heap<span style="color:#990000">[</span>hole<span style="color:#990000">]</span> <span style="color:#990000">=</span> heap<span style="color:#990000">[</span>child<span style="color:#990000">];</span> <i><span style="color:#9A1900">// move child up</span></i>
hole <span style="color:#990000">=</span> child<span style="color:#990000">;</span> <i><span style="color:#9A1900">// move hole down</span></i>
<span style="color:#FF0000">}</span> <b><span style="color:#0000FF">else</span></b> <span style="color:#FF0000">{</span>
<b><span style="color:#0000FF">break</span></b><span style="color:#990000">;</span>
<span style="color:#FF0000">}</span>
<span style="color:#FF0000">}</span>
<i><span style="color:#9A1900">// correct position found! insert at that spot</span></i>
heap<span style="color:#990000">[</span>hole<span style="color:#990000">]</span> <span style="color:#990000">=</span> x<span style="color:#990000">;</span>
<span style="color:#FF0000">}</span>
<span style="color:#009900">int</span> binary_heap<span style="color:#990000">::</span><b><span style="color:#000000">findMin</span></b><span style="color:#990000">()</span> <span style="color:#FF0000">{</span>
<b><span style="color:#0000FF">if</span></b> <span style="color:#990000">(</span>heap_size <span style="color:#990000">==</span> <span style="color:#993399">0</span><span style="color:#990000">)</span> <span style="color:#FF0000">{</span>
<b><span style="color:#0000FF">throw</span></b> <span style="color:#FF0000">"findMin() called on empty heap"</span><span style="color:#990000">;</span>
<span style="color:#FF0000">}</span>
<b><span style="color:#0000FF">return</span></b> heap<span style="color:#990000">[</span><span style="color:#993399">1</span><span style="color:#990000">];</span>
<span style="color:#FF0000">}</span>
<span style="color:#009900">unsigned</span> <span style="color:#009900">int</span> binary_heap<span style="color:#990000">::</span><b><span style="color:#000000">size</span></b><span style="color:#990000">()</span> <span style="color:#FF0000">{</span>
<b><span style="color:#0000FF">return</span></b> heap_size<span style="color:#990000">;</span>
<span style="color:#FF0000">}</span>
<span style="color:#009900">void</span> binary_heap<span style="color:#990000">::</span><b><span style="color:#000000">makeEmpty</span></b><span style="color:#990000">()</span> <span style="color:#FF0000">{</span>
heap_size <span style="color:#990000">=</span> <span style="color:#993399">0</span><span style="color:#990000">;</span>
heap<span style="color:#990000">.</span><b><span style="color:#000000">resize</span></b><span style="color:#990000">(</span><span style="color:#993399">1</span><span style="color:#990000">);</span>
<span style="color:#FF0000">}</span>
<span style="color:#009900">bool</span> binary_heap<span style="color:#990000">::</span><b><span style="color:#000000">isEmpty</span></b><span style="color:#990000">()</span> <span style="color:#FF0000">{</span>
<b><span style="color:#0000FF">return</span></b> heap_size <span style="color:#990000">==</span> <span style="color:#993399">0</span><span style="color:#990000">;</span>
<span style="color:#FF0000">}</span>
<span style="color:#009900">void</span> binary_heap<span style="color:#990000">::</span><b><span style="color:#000000">print</span></b><span style="color:#990000">()</span> <span style="color:#FF0000">{</span>
cout <span style="color:#990000"><<</span> <span style="color:#FF0000">"("</span> <span style="color:#990000"><<</span> heap<span style="color:#990000">[</span><span style="color:#993399">0</span><span style="color:#990000">]</span> <span style="color:#990000"><<</span> <span style="color:#FF0000">") "</span><span style="color:#990000">;</span>
<b><span style="color:#0000FF">for</span></b> <span style="color:#990000">(</span><span style="color:#009900">int</span> i <span style="color:#990000">=</span> <span style="color:#993399">1</span><span style="color:#990000">;</span> i <span style="color:#990000"><=</span> heap_size<span style="color:#990000">;</span> i<span style="color:#990000">++)</span> <span style="color:#FF0000">{</span>
cout <span style="color:#990000"><<</span> heap<span style="color:#990000">[</span>i<span style="color:#990000">]</span> <span style="color:#990000"><<</span> <span style="color:#FF0000">" "</span><span style="color:#990000">;</span>
<i><span style="color:#9A1900">// next line from http://tinyurl.com/mf9tbgm</span></i>
<span style="color:#009900">bool</span> isPow2 <span style="color:#990000">=</span> <span style="color:#990000">(((</span>i<span style="color:#990000">+</span><span style="color:#993399">1</span><span style="color:#990000">)</span> <span style="color:#990000">&</span> <span style="color:#990000">~(</span>i<span style="color:#990000">))==(</span>i<span style="color:#990000">+</span><span style="color:#993399">1</span><span style="color:#990000">))?</span> i<span style="color:#990000">+</span><span style="color:#993399">1</span> <span style="color:#990000">:</span> <span style="color:#993399">0</span><span style="color:#990000">;</span>
<b><span style="color:#0000FF">if</span></b> <span style="color:#990000">(</span>isPow2<span style="color:#990000">)</span> <span style="color:#FF0000">{</span>
cout <span style="color:#990000"><<</span> endl <span style="color:#990000"><<</span> <span style="color:#FF0000">"</span><span style="color:#CC33CC">\t</span><span style="color:#FF0000">"</span><span style="color:#990000">;</span>
<span style="color:#FF0000">}</span>
<span style="color:#FF0000">}</span>
cout <span style="color:#990000"><<</span> endl<span style="color:#990000">;</span>
<span style="color:#FF0000">}</span>
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