From c978b7f8feb1ea438e7d38dfd42dc35e0df0be3c Mon Sep 17 00:00:00 2001
From: Shaminda Rathnayaka <rmbsrathnayaka@gmail.com>
Date: Mon, 29 Oct 2018 13:08:10 +0530
Subject: [PATCH] add heap sort using php

---
 .../Algorithms/Heap Sort/heap_sort.php.txt    | 125 ++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100644 Algorithms/Algorithms/Heap Sort/heap_sort.php.txt

diff --git a/Algorithms/Algorithms/Heap Sort/heap_sort.php.txt b/Algorithms/Algorithms/Heap Sort/heap_sort.php.txt
new file mode 100644
index 0000000..261a2eb
--- /dev/null
+++ b/Algorithms/Algorithms/Heap Sort/heap_sort.php.txt	
@@ -0,0 +1,125 @@
+<?php
+  class Node
+  {
+  private $_i; 
+  
+  public function __construct($key)
+  {
+  $this->_i = $key;
+  }
+  
+  public function getKey()
+  {
+  return $this->_i;
+  }
+  }
+  
+  class Heap
+  {
+  private $heap_Array;
+  private $_current_Size;
+  
+  public function __construct()
+  {
+  $heap_Array = array();
+  $this->_current_Size = 0;
+  }
+  
+  // Remove item with max key 
+ public function remove()
+  {
+  $root = $this->heap_Array[0];
+  // put last element into root
+  $this->heap_Array[0] = $this->heap_Array[--$this->_current_Size];
+  $this->bubbleDown(0); 
+  return $root; 
+  }
+  
+  // Shift process
+  public function bubbleDown($index)
+  {
+  $larger_Child = null;
+  $top = $this->heap_Array[$index]; // save root
+  while ($index < (int)($this->_current_Size/2)) { // not on bottom row
+  $leftChild = 2 * $index + 1;
+  $rightChild = $leftChild + 1;
+  
+  // find larger child
+  if ($rightChild < $this->_current_Size 
+  && $this->heap_Array[$leftChild] < $this->heap_Array[$rightChild]) // right child exists?
+  {
+  $larger_Child = $rightChild;
+  } else {
+  $larger_Child = $leftChild;
+  }
+  
+  if ($top->getKey() >= $this->heap_Array[$larger_Child]->getKey()) {
+  break;
+  }
+  
+  // shift child up
+  $this->heap_Array[$index] = $this->heap_Array[$larger_Child]; 
+  $index = $larger_Child; // go down
+  }
+  
+  $this->heap_Array[$index] = $top; // root to index
+  }
+  
+  public function insertAt($index, Node $newNode)
+  {
+  $this->heap_Array[$index] = $newNode;
+  }
+  
+  public function incrementSize()
+  {
+  $this->_current_Size++;
+  }
+  
+  public function getSize()
+  {
+  return $this->_current_Size;
+  }
+  
+  public function asArray()
+  {
+  $arr = array();
+  for ($j = 0; $j < sizeof($this->heap_Array); $j++) {
+  $arr[] = $this->heap_Array[$j]->getKey();
+  }
+  
+  return $arr;
+  }
+  }
+  
+  function heapsort(Heap $Heap)
+  { 
+  $size = $Heap->getSize();
+  // "sift" all nodes, except lowest level as it has no children
+  for ($j = (int)($size/2) - 1; $j >= 0; $j--) 
+  {
+  $Heap->bubbleDown($j);
+  }
+  // sort the heap
+  for ($j = $size-1; $j >= 0; $j--) { 
+  $BiggestNode = $Heap->remove();
+  // use same nodes array for sorted elements
+  $Heap->insertAt($j, $BiggestNode);
+  }
+  
+  return $Heap->asArray(); 
+  }
+  
+  $arr = array(3, 0, 2, 5, -1, 4, 1);
+  echo "Original Array : ";
+  echo implode(', ',$arr ); 
+  $Heap = new Heap();
+  foreach ($arr as $key => $val) {
+  $Node = new Node($val);
+  $Heap->insertAt($key, $Node);
+  $Heap->incrementSize();
+  }
+  $result = heapsort($Heap);
+  echo "\nSorted Array : ";
+  echo implode(', ',$result)."\n";
+  ?>
+  
\ No newline at end of file