Lecture 7

SoSe24/lec03_sort_alg/algdat_heap.py

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+from SoSe24.algodat.foundation import AlgoDatArray
+
+
+class AlgoDatHeap():
+
+    def __init__(self, values: AlgoDatArray):
+        self.heap = values
+        self.size = len(values)
+
+    def left_child(self, i):
+        return 2*i + 1
+
+    def right_child(self, i):
+        return 2*i + 2
+
+    def parent(self, i):
+        return (i-1)//2
+
+    def max_heapify(self, i):
+        l = self.left_child(i)
+        r = self.right_child(i)
+        largest = i
+        if l <= self.size and self.heap[l-1] > self.heap[i-1]:
+            largest = l
+        if r <= self.size and self.heap[r-1] > self.heap[largest-1]:
+            largest = r
+        if largest != i:
+            self.heap[i-1], self.heap[largest-1] = self.heap[largest-1], self.heap[i-1]
+            self.max_heapify(largest)
+
+    def min_heapify(self, i):
+        l = self.left_child(i)
+        r = self.right_child(i)
+        smallest = i
+        if l <= self.size and self.heap[l-1] < self.heap[i-1]:
+            smallest = l
+        if r <= self.size and self.heap[r-1] < self.heap[smallest-1]:
+            smallest = r
+        if smallest != i:
+            self.heap[i-1], self.heap[smallest-1] = self.heap[smallest-1], self.heap[i-1]
+            self.min_heapify(smallest)
+
+    def build_max_heap(self):
+        for i in range(self.size//2, 0, -1):
+            self.max_heapify(i)
+
+    def build_min_heap(self):
+        for i in range(self.size//2, 0, -1):
+            self.min_heapify(i)
+
+    def as_list(self):
+        return [self.heap[i].value for i in range(self.size)]