diff --git a/heaps/heap_sort.py b/heaps/heap_sort.py index 3b834a5..0ce238e 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 log n) + Space Complexity: O(n) """ - pass \ No newline at end of file + heap = MinHeap() + + for num in list: + heap.add(num) + + i = 0 + while not heap.empty(): + list[i] = heap.remove() + i+= 1 + + return list \ No newline at end of file diff --git a/heaps/min_heap.py b/heaps/min_heap.py index 0095872..f3d1a5c 100644 --- a/heaps/min_heap.py +++ b/heaps/min_heap.py @@ -21,19 +21,31 @@ 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 self.empty(): + return None + + self.swap(0, len(self.store) -1) + min = self.store.pop() + self.heap_down(0) + return min.value def __str__(self): @@ -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 +71,18 @@ 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 index + + parentIndex = (index-1) // 2 + + if self.store[parentIndex].key > self.store[index].key: + self.swap(parentIndex, index) + self.heap_up(parentIndex) + def heap_down(self, index): """ This helper method takes an index and @@ -70,7 +90,21 @@ def heap_down(self, index): larger than either of its children and continues until the heap property is reestablished. """ - pass + leftIndex = (2 * index) + 1 + rightIndex = (2 * index) + 2 + + if leftIndex < len(self.store): + if rightIndex < len(self.store): + if self.store[leftIndex].key < self.store[rightIndex].key: + minIndex = leftIndex + else: + minIndex = rightIndex + else: + minIndex = leftIndex + + if self.store[index].key > self.store[minIndex].key: + self.swap(index, minIndex) + self.heap_down(minIndex) def swap(self, index_1, index_2):