diff --git a/heaps/heap_sort.py b/heaps/heap_sort.py index 3b834a5..36b744a 100644 --- a/heaps/heap_sort.py +++ 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) + Space Complexity: O(1) """ - pass \ No newline at end of file + heap = MinHeap() + + for num in list: + heap.add(num) + + index = 0 + + while not heap.empty(): + list[index] = heap.remove() + index += 1 + return list \ No newline at end of file diff --git a/heaps/min_heap.py b/heaps/min_heap.py index 0095872..efe1d05 100644 --- a/heaps/min_heap.py +++ b/heaps/min_heap.py @@ -1,5 +1,5 @@ class HeapNode: - + def __init__(self, key, value): self.key = key self.value = value @@ -21,19 +21,29 @@ def __init__(self): 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(log n) """ - pass + if value == None: + value = key + + node = HeapNode(key, value) + self.store.append(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(log n) """ - 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): @@ -49,7 +59,7 @@ def empty(self): Time complexity: ? Space complexity: ? """ - pass + return len(self.store) == 0 def heap_up(self, index): @@ -62,7 +72,14 @@ def heap_up(self, index): Time complexity: ? Space complexity: ? """ - pass + if index == 0: + return + + parent = (index -1) // 2 + if self.store[index].key < self.store[parent].key: + self.swap(index, parent) + self.heap_up(parent) + def heap_down(self, index): """ This helper method takes an index and @@ -70,8 +87,20 @@ def heap_down(self, index): larger than either of its children and continues until the heap property is reestablished. """ - pass - + left_child = (2 * index) + 1 + right_child = (2 * index) + 2 + + if left_child < len(self.store): + if right_child < len(self.store): + if self.store[left_child.key] < self.store[right_child].key: + min_child = left_child + else: + min_child = right_child + else: min_child = left_child + + if self.store[index].key > self.store[min_child.key]: + self.swap(index, min_child) + self.heap_down(min_child) def swap(self, index_1, index_2): """ Swaps two elements in self.store