diff --git a/heaps/heap_sort.py b/heaps/heap_sort.py index 3b834a5..ec97640 100644 --- a/heaps/heap_sort.py +++ b/heaps/heap_sort.py @@ -1,8 +1,17 @@ +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 \ No newline at end of file + heap = MinHeap() + for num in list: + heap.add(num) + + heap_list = [] + while heap.store: + num = heap.remove() + heap_list.append(num) + return heap_list \ No newline at end of file diff --git a/heaps/min_heap.py b/heaps/min_heap.py index 0095872..476a29a 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 @@ -21,18 +21,30 @@ 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(1) """ - 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(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 @@ -46,10 +58,10 @@ def __str__(self): 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): @@ -59,10 +71,16 @@ def heap_up(self, index): property is reestablished. This could be **very** helpful for the add method. - Time complexity: ? - Space complexity: ? + Time complexity: O(1) + Space complexity: O(1) """ - pass + if index == 0: + return None + + 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 @@ -70,7 +88,16 @@ def heap_down(self, index): larger than either of its children and continues until the heap property is reestablished. """ - pass + min_child_index = 2 * index + 1 + child2_index = 2 * index + 2 + if child2_index < len(self.store) and self.store[child2_index].key < self.store[min_child_index].key: + min_child_index = child2_index + + if min_child_index >= len(self.store): + return None + elif self.store[min_child_index].key < self.store[index].key: + self.swap(index, min_child_index) + self.heap_down(min_child_index) def swap(self, index_1, index_2):