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Update persistent_segment_tree.py

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Putul Singh 2024-10-19 16:49:21 +05:30 committed by GitHub
parent eaafd1ca3c
commit 124b177795
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1 changed files with 7 additions and 14 deletions
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data_structures/persistent_segment_tree.py
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@ -1,13 +1,11 @@
from __future__ import annotations from __future__ import annotations
class Node: class Node:
def __init__(self, value: int = 0) -> None: def __init__(self, value: int = 0) -> None:
self.value: int = value self.value: int = value
self.left: Node | None = None self.left: Node | None = None
self.right: Node | None = None self.right: Node | None = None
class PersistentSegmentTree: class PersistentSegmentTree:
def __init__(self, arr: list[int]) -> None: def __init__(self, arr: list[int]) -> None:
self.n: int = len(arr) self.n: int = len(arr)
@ -78,14 +76,12 @@ class PersistentSegmentTree:
if index <= mid: if index <= mid:
new_node.left = self._update(node.left, start, mid, index, value) new_node.left = self._update(node.left, start, mid, index, value)
new_node.right = node.right new_node.right = node.right # Ensure right node is the same as the original
else: else:
new_node.left = node.left new_node.left = node.left # Ensure left node is the same as the original
new_node.right = self._update(node.right, mid + 1, end, index, value) new_node.right = self._update(node.right, mid + 1, end, index, value)
new_node.value = (new_node.left.value if new_node.left else 0) + ( new_node.value = new_node.left.value + (new_node.right.value if new_node.right else 0)
new_node.right.value if new_node.right else 0
)
return new_node return new_node
@ -101,7 +97,7 @@ class PersistentSegmentTree:
>>> version_1 = pst.update(0, 1, 5) # Update index 1 to 5 >>> version_1 = pst.update(0, 1, 5) # Update index 1 to 5
>>> pst.query(version_1, 0, 3) # Sum of all elements in new version >>> pst.query(version_1, 0, 3) # Sum of all elements in new version
13 13
>>> pst.query(version_1, 1, 2) # Sum of elements at index 1 and 2 in new version >>> pst.query(version_1, 1, 2) # Sum of elements at index 1 and 2
8 8
""" """
return self._query(self.roots[version], 0, self.n - 1, left, right) return self._query(self.roots[version], 0, self.n - 1, left, right)
@ -119,20 +115,17 @@ class PersistentSegmentTree:
>>> pst._query(root, 0, 3, 2, 3) # Sum of elements at index 2 and 3 >>> pst._query(root, 0, 3, 2, 3) # Sum of elements at index 2 and 3
7 7
""" """
if left > end or right < start: if node is None or left > end or right < start:
return 0 return 0
if left <= start and right >= end: if left <= start and right >= end:
return node.value return node.value
mid = (start + end) // 2 mid = (start + end) // 2
return self._query(node.left, start, mid, left, right) + self._query( return (self._query(node.left, start, mid, left, right) +
node.right, mid + 1, end, left, right self._query(node.right, mid + 1, end, left, right))
)
# Running the doctests # Running the doctests
if __name__ == "__main__": if __name__ == "__main__":
import doctest import doctest
print("Running doctests...") print("Running doctests...")
result = doctest.testmod() result = doctest.testmod()
print(f"Ran {result.attempted} tests, {result.failed} failed.") print(f"Ran {result.attempted} tests, {result.failed} failed.")