Day-52 Heap Sort 2

Author: mandliya

README.md

@@ -4,9 +4,9 @@
 
 | Current Status|     Stats     |
 | :------------: | :----------: |
-| Total Problems | 71 |
-| Current Streak | 51 |
-| Longest Streak | 51 ( August 17, 2015 - October 6, 2015 ) |
+| Total Problems | 72 |
+| Current Streak | 52 |
+| Longest Streak | 52 ( August 17, 2015 - October 7, 2015 ) |
 
 </center>
 
@@ -45,6 +45,7 @@ Include contains single header implementation of data structures and some algori
 | Bubble Sort Implementation | [bubbleSort.h] (include/bubbleSort.h) |
 | Linux Kernel Double LinkedList Implementation | [double_linked_list.h](include/double_linked_list.h) |
 | Generic Graph Implementation (Adjacency List) | [graph.h](include/graph.h) |
+| Heap Sort Implementation | [heap_sort.h](include/heap_sort.h)|
 
 ###Bit Manipulation Problems
 | Problem | Solution |

include/heap_sort.h

@@ -0,0 +1,60 @@
+#ifndef HEAP_SORT
+#define HEAP_SORT
+
+#include <generic.h>
+#include <cassert>
+
+namespace algo {
+
+    template <typename T>
+      static void __sift_down(T list[], int low, int high) {
+        int root = low;
+        while( (root * 2 + 1) <= high ) {
+          int left_child = root * 2 + 1;
+          int right_child = left_child + 1;
+          int swpIdx = root;
+          //if root is less than left child.
+          if ( list[root] < list[left_child] ) {
+            swpIdx = left_child;
+          }
+          // if right child exists and bigger
+          if ( (right_child <= high) && list[swpIdx] < list[right_child] ) {
+            swpIdx = right_child;
+          }
+
+          if ( swpIdx != root ) {
+            algo::swap( list[swpIdx], list[root] );
+          } else {
+            break;
+          }
+          //keep going down
+          swpIdx = root;
+        }
+      }
+
+    template <typename T>
+      static void __heapify(T list[], int low, int high) {
+        int mid = (high - low - 1)/2;
+        while( mid >=0 ) {
+          __sift_down(list, mid, high);
+          --mid;
+        }
+      }
+
+    template <typename T>
+      static void heap_sort(T list[], int size) {
+        assert(list);
+        assert(size > 0);
+
+        //heapify the list
+        __heapify(list, 0, size-1);
+
+        int high = size - 1;
+        while ( high > 0 ) {
+          algo::swap(list[high], list[0]);
+          --high;
+          __heapify(list, 0, high);
+        }
+      }
+}
+#endif

sort_search_problems/heapSortDemo.cpp

@@ -0,0 +1,30 @@
+#include <generic.h>
+#include <heap_sort.h>
+
+int main()
+{
+  const int MAX_ELEMENTS = 10;
+  int arr[MAX_ELEMENTS];
+  double arrD[MAX_ELEMENTS];
+
+  //Filling up the array with random numbers;
+  for (int i = 0; i < MAX_ELEMENTS; ++i)
+  {
+      arr[i] = algo::random_range(1, 100);
+      arrD[i] = algo::random_range(1.0, 99.99);
+  }
+
+  std::cout << "Before Sorting:\n";
+  algo::printList(arr, MAX_ELEMENTS);
+  algo::heap_sort(arr, MAX_ELEMENTS);
+  std::cout << "After Sorting:\n";
+  algo::printList(arr, MAX_ELEMENTS);
+
+
+  std::cout << "\n\nBefore Sorting:\n";
+  algo::printList(arrD, MAX_ELEMENTS);
+  algo::heap_sort(arrD, MAX_ELEMENTS);
+  std::cout << "After Sorting:\n";
+  algo::printList(arrD, MAX_ELEMENTS);
+  return 0;
+}