Symone B.

heaps/heap_sort.py

@@ -1,8 +1,18 @@
-
+from heaps.min_heap import MinHeap
 
 def heap_sort(list):
     """ This method uses a heap to sort an array.
-        Time Complexity:  ?
-        Space Complexity: ?
+        Time Complexity:  O(n log n)
+        Space Complexity: O(n)
     """
-    pass
+
+    heap = MinHeap()
+    for element in list:
+        heap.add(element)
+
+    index = 0
+    while not heap.empty():
+        list[index] = heap.remove()
+        index += 1
+
+    return list

heaps/min_heap.py

@@ -1,5 +1,5 @@
 class HeapNode:
-  
+
     def __init__(self, key, value):
         self.key = key
         self.value = value
@@ -15,39 +15,63 @@ class MinHeap:
     def __init__(self):
         self.store = []
 
+    # helpers
+    def parent_index(self, index):
+        return (index - 1) // 2
+
+    def left_child_index(self, index):
+        return (2 * index) + 1
+
+    def right_child_index(self, index):
+        return (2 * index) + 2
+
 
     def add(self, key, value = None):
         """ This method adds a HeapNode instance to the heap
             If value == None the new node's value should be set to key
-            Time Complexity: ?
-            Space Complexity: ?
+            Time Complexity: O(log n)
+            Space Complexity: O(1)
         """
-        pass
+
+        if value is None:
+            value = key
+
+        new_node = HeapNode(key, value)
+        self.store.append(new_node)
+        self.heap_up(len(self.store) - 1) 
+
 
     def remove(self):
         """ This method removes and returns an element from the heap
             maintaining the heap structure
-            Time Complexity: ?
-            Space Complexity: ?
+            Time Complexity: O(log n)
+            Space Complexity: O(1)
         """
-        pass
+
+        if len(self.store) == 0:
+            return
+
+        self.swap(0, len(self.store) - 1)
+        min = self.store.pop()
+        self.heap_down(0)
+
+        return min.value
 
 
-
     def __str__(self):
-        """ This method lets you print the heap, when you're testing your app.
-        """
+        """ This method lets you print the heap, when you're testing your app."""
+
         if len(self.store) == 0:
             return "[]"
         return f"[{', '.join([str(element) for element in self.store])}]"
 
 
     def empty(self):
         """ This method returns true if the heap is empty
-            Time complexity: ?
-            Space complexity: ?
+            Time complexity: O(1)
+            Space complexity: O(1)
         """
-        pass
+        return len(self.store) == 0
 
 
     def heap_up(self, index):
@@ -57,25 +81,43 @@ def heap_up(self, index):
             property is reestablished.
 
             This could be **very** helpful for the add method.
-            Time complexity: ?
-            Space complexity: ?
+            Time complexity: O(log n)
+            Space complexity: O(1)
         """
-        pass
+
+        if index == 0:
+            return
+
+        if self.store[self.parent_index(index)].key > self.store[index].key:
+            self.swap(self.parent_index(index), index)
+            self.heap_up(self.parent_index(index))
+
 
     def heap_down(self, index):
         """ This helper method takes an index and 
             moves the corresponding element down the heap if it's 
             larger than either of its children and continues until
             the heap property is reestablished.
         """
-        pass
+
+        if self.left_child_index(index) < len(self.store):
+            if self.right_child_index(index) < len(self.store):
+                if self.store[self.left_child_index(index)].key < self.store[self.right_child_index(index)].key:
+                    smaller_node = self.left_child_index(index)
+                else:
+                    smaller_node = self.right_child_index(index)
+            else:
+                smaller_node = self.left_child_index(index)
+            if self.store[index].key > self.store[smaller_node].key:
+                self.swap(index, smaller_node)
+                self.heap_down(smaller_node)
 
 
     def swap(self, index_1, index_2):
         """ Swaps two elements in self.store
             at index_1 and index_2
             used for heap_up & heap_down
         """
-        temp = self.store[index_1]
-        self.store[index_1] = self.store[index_2]
-        self.store[index_2] = temp
+
+        self.store[index_1], self.store[index_2] = self.store[index_2], self.store[index_1]
+