From 10ea1ebfac23be2ca23047dc2970a20fca1c5eeb Mon Sep 17 00:00:00 2001
From: Abhishek Mehra <52788025+Triaro@users.noreply.github.com>
Date: Fri, 2 Oct 2020 10:55:36 +0530
Subject: [PATCH] heap_sort.m

sorting algorithm
---
 algorithms/sorting/heap_sort.m | 40 ++++++++++++++++++++++++++++++++++
 1 file changed, 40 insertions(+)
 create mode 100644 algorithms/sorting/heap_sort.m

diff --git a/algorithms/sorting/heap_sort.m b/algorithms/sorting/heap_sort.m
new file mode 100644
index 0000000..df52e1e
--- /dev/null
+++ b/algorithms/sorting/heap_sort.m
@@ -0,0 +1,40 @@
+function list = heapSort(list)
+ 
+    function list = siftDown(list,root,theEnd) 
+        while (root * 2) <= theEnd
+ 
+            child = root * 2;
+            if (child + 1 <= theEnd) && (list(child) < list(child+1))
+                child = child + 1;
+            end
+ 
+            if list(root) < list(child)
+                list([root child]) = list([child root]); %Swap
+                root = child;
+            else
+                return
+            end
+ 
+        end %while
+    end %siftDown
+ 
+    count = numel(list);
+ 
+    %Because heapify is called once in pseudo-code, it is inline here
+    start = floor(count/2);
+ 
+    while start >= 1
+        list = siftDown(list, start, count);
+        start = start - 1;
+    end
+    %End Heapify
+ 
+    while count > 1
+ 
+        list([count 1]) = list([1 count]); %Swap        
+        count = count - 1;
+        list = siftDown(list,1,count);
+ 
+    end
+ 
+end