From 238909730dc5d2d7dad5430c2dcc0da10adede8a Mon Sep 17 00:00:00 2001
From: nryoung <nryoung@gmail.com>
Date: Tue, 28 Aug 2012 11:35:22 -0600
Subject: [PATCH] Added skeleton code for heap sort

---
 algorithms/sorting/heap_sort.py  | 43 ++++++++++++++++++++++++++++++++
 algorithms/tests/test_sorting.py | 15 +++++++++--
 requirements.txt                 |  4 +++
 3 files changed, 60 insertions(+), 2 deletions(-)
 create mode 100644 algorithms/sorting/heap_sort.py
 create mode 100644 requirements.txt

diff --git a/algorithms/sorting/heap_sort.py b/algorithms/sorting/heap_sort.py
new file mode 100644
index 0000000..968605f
--- /dev/null
+++ b/algorithms/sorting/heap_sort.py
@@ -0,0 +1,43 @@
+""" Implementation of Heap Sort """
+
+def parent(i):
+    return i/2
+
+def left(i):
+    return 2*i
+
+def right(i):
+    return 2*i+1
+
+def max_heapify(seq, i, n):
+    l = left(i)
+    r = right(i)
+
+    if l <= n and seq[n] > seq[i]:
+        largest = l
+    else:
+        largest = i
+    if r <= n and seq[r] > seq[largest]:
+        largest = r
+    
+    if largest != i:
+        seq[i], seq[largest] = seq[largest], seq[i]
+        max_heapify(seq, largest, n)
+
+def heap_length(seq):
+    return len(seq) - 1
+
+def build_heap(seq):
+    n = heap_length(seq)
+    for i in range(n/2,0,-1):
+        max_heapify(seq, i, n)
+
+def sort(seq):
+    build_heap(seq)
+    heap_size = heap_length(seq)
+    for i in range(heap_size,1,-1):
+        seq[1], seq[i] = seq[i], seq[1]
+        heap_size = heap_size - 1
+        max_heapify(seq, 1, heap_size)
+    
+    return seq
diff --git a/algorithms/tests/test_sorting.py b/algorithms/tests/test_sorting.py
index 61d89c9..b9e747c 100644
--- a/algorithms/tests/test_sorting.py
+++ b/algorithms/tests/test_sorting.py
@@ -1,6 +1,6 @@
 import random
 import unittest
-from ..sorting import bubble_sort, selection_sort, insertion_sort, merge_sort, quick_sort
+from ..sorting import bubble_sort, selection_sort, insertion_sort, merge_sort, quick_sort, heap_sort
 
 class TestBubbleSort(unittest.TestCase):
     """
@@ -57,7 +57,6 @@ def test_merge(self):
 class TestQuickSort(unittest.TestCase):
     """
     Test Quick sort on a small range from 0-9
-    also tests partition function included in quick sort.
     """
 
     def test_quicksort(self):
@@ -66,3 +65,15 @@ def test_quicksort(self):
         self.seq = quick_sort.sort(self.seq)
         self.assertIs(self.seq[0], 0)
         self.assertIs(self.seq[-1], 9)
+
+class TestHeapSort(unittest.TestCase):
+    """
+    Test Heap sort on a small range from 0-9
+    """
+
+    def test_heapsort(self):
+        self.seq = range(10)
+        random.shuffle(self.seq)
+        self.seq = heap_sort.sort(self.seq)
+        self.assertIs(self.seq[0], 0)
+        self.assertIs(self.seq[-1], 9)
diff --git a/requirements.txt b/requirements.txt
new file mode 100644
index 0000000..65d9a46
--- /dev/null
+++ b/requirements.txt
@@ -0,0 +1,4 @@
+argparse==1.2.1
+distribute==0.6.27
+nose==1.1.2
+wsgiref==0.1.2