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105 lines
2.2 KiB
Python
105 lines
2.2 KiB
Python
# https://en.wikipedia.org/wiki/Treap
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import random
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import time
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class Treap:
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def __init__(self, key):
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self.key = key
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self.prio = random.randint(0, 1000000000)
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self.size = 1
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self.left = None
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self.right = None
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def update(self):
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self.size = 1 + size(self.left) + size(self.right)
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def size(treap):
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return 0 if treap is None else treap.size
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def split(root, minRight):
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if root is None:
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return None, None
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if root.key >= minRight:
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left, right = split(root.left, minRight)
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root.left = right
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root.update()
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return left, root
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else:
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left, right = split(root.right, minRight)
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root.right = left
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root.update()
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return root, right
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def merge(left, right):
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if left is None:
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return right
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if right is None:
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return left
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if left.prio > right.prio:
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left.right = merge(left.right, right)
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left.update()
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return left
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else:
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right.left = merge(left, right.left)
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right.update()
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return right
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def insert(root, key):
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left, right = split(root, key)
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return merge(merge(left, Treap(key)), right)
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def remove(root, key):
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left, right = split(root, key)
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return merge(left, split(right, key + 1)[1])
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def kth(root, k):
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if k < size(root.left):
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return kth(root.left, k)
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elif k > size(root.left):
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return kth(root.right, k - size(root.left) - 1)
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return root.key
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def print_treap(root):
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def dfs_print(root):
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if root is None:
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return
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dfs_print(root.left)
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print(str(root.key) + ' ', end='')
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dfs_print(root.right)
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dfs_print(root)
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print()
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def test():
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start = time.time()
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treap = None
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s = set()
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for i in range(100000):
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key = random.randint(0, 10000)
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if random.randint(0, 1) == 0:
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if key in s:
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treap = remove(treap, key)
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s.remove(key)
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elif key not in s:
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treap = insert(treap, key)
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s.add(key)
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assert len(s) == size(treap)
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for i in range(size(treap)):
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assert kth(treap, i) in s
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print(time.time() - start)
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test()
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