lecture 5

SoSe24/lec03_sort_alg/quick_sort.py

 
 def quick_sort(z: AlgoDatArray, left: int, right: int):
     if left < right:
-        q = partition(z, left, right)
-        #q = median_pivot(z, left, right)
+        #q = partition(z, left, right)
+        q = median_pivot(z, left, right)
         quick_sort(z, left, q-1)
         quick_sort(z, q+1, right)
 

SoSe24/lec04_trees/avl_tree.py

+from SoSe24.algodat.foundation import AlgoDatArray, AlgoDatValue, read_int_sequence
+from SoSe24.lec04_trees.bin_tree import BinTree, BinTreeNode
+from time import perf_counter as pfc
+
+class AVLTreeNode(BinTreeNode):
+    def __init__(self, value: AlgoDatValue):
+        super().__init__(value)
+        self.parent = None
+        self.balance = 0
+
+    def update_balance(self):
+        left_height = self.left.height() if self.left else 0
+        right_height = self.right.height() if self.right else 0
+        self.balance = right_height - left_height
+
+    def right_rotate(self) -> BinTreeNode:
+        new_root = self.left
+        new_root.parent = self.parent
+        self.left = new_root.right
+        if self.left:
+            self.left.parent = self
+        new_root.right = self
+        self.parent = new_root
+        if new_root.parent:
+            if new_root.parent.left == self:
+                new_root.parent.left = new_root
+            else:
+                new_root.parent.right = new_root
+        self.update_balance()
+        new_root.update_balance()
+        return new_root
+
+    def left_rotate(self) -> BinTreeNode:
+        new_root = self.right
+        new_root.parent = self.parent
+        self.right = new_root.left
+        if self.right:
+            self.right.parent = self
+        new_root.left = self
+        self.parent = new_root
+        if new_root.parent:
+            if new_root.parent.left == self:
+                new_root.parent.left = new_root
+            else:
+                new_root.parent.right = new_root
+        self.update_balance()
+        new_root.update_balance()
+        return new_root
+
+    def right_left_rotate(self) -> BinTreeNode:
+        self.right = self.right.right_rotate()
+        return self.left_rotate()
+
+    def left_right_rotate(self) -> BinTreeNode:
+        self.left = self.left.left_rotate()
+        return self.right_rotate()
+
+class AVLTree(BinTree):
+
+    def new_node(self, value: AlgoDatValue):
+        return AVLTreeNode(value)
+
+    def balance(self, node: AVLTreeNode):
+        node.update_balance()
+        if node.balance == -2:
+            if node.left.balance <= 0:
+                node = node.right_rotate()
+            else:
+                node = node.left_right_rotate()
+        elif node.balance == 2:
+            if node.right.balance >= 0:
+                node = node.left_rotate()
+            else:
+                node = node.right_left_rotate()
+        if node.parent:
+            self.balance(node.parent)
+        else:
+            self.root = node
+
+    def insert(self, value: AlgoDatValue):
+        node, parent = super().insert(value)
+        node.parent = parent
+        if parent:
+            self.balance(parent)
+        return node, parent
+
+    def delete(self, value: AlgoDatValue):
+        node, parent = super().delete(value)
+        if node:
+            node.parent = parent
+        if parent:
+            self.balance(parent)
+
+
+
+if __name__ == "__main__":
+    z = read_int_sequence("../../seq0.txt")
+    print(z, len(z))
+    start = pfc()
+    tree = AVLTree()
+    for i in z:
+        tree.insert(i)
+    tree.walk()
+    tree.tree_walk()
+    tree.levelwalk()
+    #tree.graph_walk()
+    tree.delete(AlgoDatValue(46))
+    tree.delete(AlgoDatValue(48))
+    tree.graph_walk()
+    print(f"Dauer: {pfc() - start:.4f}s")
+    AlgoDatValue.summary()

SoSe24/lec04_trees/avl_tree_plot.py

+from SoSe24.algodat.foundation import AlgoDatArray, AlgoDatValue, read_int_sequence, read_int_sequence_limited
+import matplotlib
+matplotlib.use('TkAgg')
+import matplotlib.pyplot as plt
+import avl_tree as avl
+
+if __name__ == "__main__":
+    filename = "../../seq3_sorted.txt"
+    #filename = "../../seq3.txt"
+    dummy = read_int_sequence(filename)
+    n = len(dummy)
+    step = n // 100
+
+    memory_values = []
+    compare_values = []
+
+    for right_end in range(1, n, step):
+        AlgoDatValue.reset()
+        z = read_int_sequence_limited(filename, right_end)
+        tree = avl.AVLTree()
+        for i in z:
+            tree.insert(i)
+        memory_values.append(AlgoDatValue.memory)
+        compare_values.append(AlgoDatValue.compare)
+
+    plt.plot(range(1, n, step), memory_values, 'b', label='Memory')
+    plt.plot(range(1, n, step), compare_values, 'r', label='Compare')
+    plt.legend()
+    plt.show()

SoSe24/lec04_trees/bin_tree.py

+from SoSe24.algodat.foundation import AlgoDatArray, AlgoDatValue, read_int_sequence
+from time import perf_counter as pfc
+
+class BinTreeNode:
+    def __init__(self, value: AlgoDatValue):
+        self.value = value
+        self.left = None
+        self.right = None
+
+    def __str__(self):
+        return f"{self.value}"
+
+    def height(self) -> int:
+        left_height = self.left.height() if self.left else 0
+        right_height = self.right.height() if self.right else 0
+        return 1 + max(left_height, right_height)
+
+
+
+class BinTree:
+    def __init__(self):
+        self.root = None
+
+    def new_node(self, value: AlgoDatValue) -> BinTreeNode:
+        return BinTreeNode(value)
+
+    def insert(self, value: AlgoDatValue) -> (BinTreeNode, BinTreeNode):
+        if not self.root:
+            self.root = self.new_node(value)
+            return self.root, None
+
+        current = self.root
+        while True:
+            if value < current.value:
+                if current.left:
+                    current = current.left
+                else:
+                    current.left = self.new_node(value)
+                    return current.left, current
+            elif value >= current.value:
+                if current.right:
+                    current = current.right
+                else:
+                    current.right = self.new_node(value)
+                    return current.right, current
+            else:
+                return None, None
+
+    def search(self, value: AlgoDatValue) -> BinTreeNode:
+        current = self.root
+        while current:
+            if value < current.value:
+                current = current.left
+            elif value > current.value:
+                current = current.right
+            else:
+                return current
+        return None
+
+    def delete(self, value: AlgoDatValue):
+        parent = None
+        current = self.root
+        while current:
+            if value < current.value:
+                parent = current
+                current = current.left
+            elif value > current.value:
+                parent = current
+                current = current.right
+            else:
+                break
+        else:
+            return None, None
+
+        if current.left and current.right:
+            parent = current
+            successor = current.right
+            while successor.left:
+                parent = successor
+                successor = successor.left
+            current.value.value = successor.value.value
+            current = successor
+
+        if current.left:
+            child = current.left
+        else:
+            child = current.right
+
+        if not parent:
+            self.root = child
+            return child, None
+        elif parent.left == current:
+            parent.left = child
+            return child, parent
+        else:
+            parent.right = child
+            return child, parent
+
+    def walk(self): # in-order
+        print("[ ", end="")
+        self.walk_recursive(self.root, 0, 0)
+        print(" ]")
+
+
+    def graph_walk(self):
+        self.leaf_counter = 0
+        with open("../../graph.gv", "w") as file:
+            file.write("digraph BST {\n")
+            file.write("    node [fontname=\"Arial\"];\n")
+            self.graph_walk_recursive(self.root, file)
+            file.write("}")
+
+    def graph_walk_recursive(self, current, file):
+        if current is not None:
+            if current.left:
+                file.write(f"{current.value} -> {current.left.value}; \n")
+                self.graph_walk_recursive(current.left, file)
+            else:
+                file.write(f"left{self.leaf_counter} [shape=point]; \n")
+                file.write(f"{current.value} -> left{self.leaf_counter}; \n")
+                self.leaf_counter += 1
+            if current.right:
+                file.write(f"{current.value} -> {current.right.value}; \n")
+                self.graph_walk_recursive(current.right, file)
+            else:
+                file.write(f"right{self.leaf_counter} [shape=point]; \n")
+                file.write(f"{current.value} -> right{self.leaf_counter}; \n")
+                self.leaf_counter += 1
+
+
+    def tree_walk(self):
+        self.walk_recursive(self.root, 0, 1)
+
+    def walk_recursive(self, node: BinTreeNode, level = 0, increase = 1):
+        if node:
+            if increase >= 1:
+                end = "\n"
+            else:
+                end = " "
+            self.walk_recursive(node.left, level+increase, increase)
+            print(" "*level*3 + str(node.value), end=end)
+            self.walk_recursive(node.right, level+increase, increase)
+
+    def levelwalk(self):
+        if self.root is None:
+            return
+        queue = [self.root]
+        while queue:
+            current = queue.pop(0)
+            print(current.value, end=" ")
+            if current.left:
+                queue.append(current.left)
+            if current.right:
+                queue.append(current.right)
+        print()
+
+
+if __name__ == "__main__":
+    z = read_int_sequence("../../seq0.txt")
+    print(z, len(z))
+    start = pfc()
+    tree = BinTree()
+    for i in z:
+        tree.insert(i)
+    tree.walk()
+    tree.tree_walk()
+    tree.levelwalk()
+    tree.delete(AlgoDatValue(46))
+    tree.graph_walk()
+    print(f"Dauer: {pfc() - start:.4f}s")
+    AlgoDatValue.summary()

SoSe24/lec04_trees/bin_tree_plot.py

+from SoSe24.algodat.foundation import AlgoDatArray, AlgoDatValue, read_int_sequence, read_int_sequence_limited
+import matplotlib
+matplotlib.use('TkAgg')
+import matplotlib.pyplot as plt
+import bin_tree as bt
+
+if __name__ == "__main__":
+    filename = "../../seq3_sorted.txt"
+    #filename = "../../seq3.txt"
+    dummy = read_int_sequence(filename)
+    n = len(dummy)
+    step = n // 100
+
+    memory_values = []
+    compare_values = []
+
+    for right_end in range(1, n, step):
+        AlgoDatValue.reset()
+        z = read_int_sequence_limited(filename, right_end)
+        tree = bt.BinTree()
+        for i in z:
+            tree.insert(i)
+        memory_values.append(AlgoDatValue.memory)
+        compare_values.append(AlgoDatValue.compare)
+
+    plt.plot(range(1, n, step), memory_values, 'b', label='Memory')
+    plt.plot(range(1, n, step), compare_values, 'r', label='Compare')
+    plt.legend()
+    plt.show()