heap sort

Author: adaugochi

leetcode/heap-sort/sort-an-array/adaa-mgbede.php

@@ -0,0 +1,35 @@
+<?php
+
+/**
+ * @param Integer[] $nums
+ * @return Integer[]
+ */
+function sortArray($nums) {
+    $n = count($nums);
+
+    $heapSize = (int)($n/2) - 1;
+
+    for ($i = $heapSize; $i >= 0; $i--) {
+        maxHeap($nums, $n, $i);
+    }
+
+    for ($i = $n; $i >= 2; $i--) {
+        $k = $i - 1;
+        list($nums[$k], $nums[0]) = [$nums[0], $nums[$k]];
+        maxHeap($nums, $k, 0);
+    }
+    return $nums;
+}
+
+function maxHeap(&$arr, $n, $i) {
+    $j = $i;
+    $l = (2 * $i) + 1;
+    $r = (2 * $i) + 2;
+    if($l < $n && $arr[$l] > $arr[$j]) $j = $l;
+    if($r < $n && $arr[$r] > $arr[$j]) $j = $r;
+
+    if ($j != $i) {
+        list($arr[$j], $arr[$i]) = [$arr[$i], $arr[$j]];
+        maxHeap($arr, $n, $j);
+    }
+}