from __future__ import annotations from random import random class Node: """ Treap's node Treap is a binary tree by value and heap by priority """ def __init__(self, value: int | None = None): self.value = value self.prior = random() self.left: Node | None = None self.right: Node | None = None def __repr__(self) -> str: from pprint import pformat if self.left is None and self.right is None: return f"'{self.value}: {self.prior:.5}'" else: return pformat( {f"{self.value}: {self.prior:.5}": (self.left, self.right)}, indent=1 ) def __str__(self) -> str: value = str(self.value) + " " left = str(self.left or "") right = str(self.right or "") return value + left + right def split(root: Node | None, value: int) -> tuple[Node | None, Node | None]: """ We split current tree into 2 trees with value: Left tree contains all values less than split value. Right tree contains all values greater or equal, than split value """ if root is None: # None tree is split into 2 Nones return None, None elif root.value is None: return None, None else: if value < root.value: """ Right tree's root will be current node. Now we split(with the same value) current node's left son Left tree: left part of that split Right tree's left son: right part of that split """ left, root.left = split(root.left, value) return left, root else: """ Just symmetric to previous case """ root.right, right = split(root.right, value) return root, right def merge(left: Node | None, right: Node | None) -> Node | None: """ We merge 2 trees into one. Note: all left tree's values must be less than all right tree's """ if (not left) or (not right): # If one node is None, return the other return left or right elif left.prior < right.prior: """ Left will be root because it has more priority Now we need to merge left's right son and right tree """ left.right = merge(left.right, right) return left else: """ Symmetric as well """ right.left = merge(left, right.left) return right def insert(root: Node | None, value: int) -> Node | None: """ Insert element Split current tree with a value into left, right, Insert new node into the middle Merge left, node, right into root """ node = Node(value) left, right = split(root, value) return merge(merge(left, node), right) def erase(root: Node | None, value: int) -> Node | None: """ Erase element Split all nodes with values less into left, Split all nodes with values greater into right. Merge left, right """ left, right = split(root, value - 1) _, right = split(right, value) return merge(left, right) def inorder(root: Node | None) -> None: """ Just recursive print of a tree """ if not root: # None return else: inorder(root.left) print(root.value, end=",") inorder(root.right) def interact_treap(root: Node | None, args: str) -> Node | None: """ Commands: + value to add value into treap - value to erase all nodes with value >>> root = interact_treap(None, "+1") >>> inorder(root) 1, >>> root = interact_treap(root, "+3 +5 +17 +19 +2 +16 +4 +0") >>> inorder(root) 0,1,2,3,4,5,16,17,19, >>> root = interact_treap(root, "+4 +4 +4") >>> inorder(root) 0,1,2,3,4,4,4,4,5,16,17,19, >>> root = interact_treap(root, "-0") >>> inorder(root) 1,2,3,4,4,4,4,5,16,17,19, >>> root = interact_treap(root, "-4") >>> inorder(root) 1,2,3,5,16,17,19, >>> root = interact_treap(root, "=0") Unknown command """ for arg in args.split(): if arg[0] == "+": root = insert(root, int(arg[1:])) elif arg[0] == "-": root = erase(root, int(arg[1:])) else: print("Unknown command") return root def main() -> None: """After each command, program prints treap""" root = None print( "enter numbers to create a tree, + value to add value into treap, " "- value to erase all nodes with value. 'q' to quit. " ) args = input() while args != "q": root = interact_treap(root, args) print(root) args = input() print("good by!") if __name__ == "__main__": import doctest doctest.testmod() main()