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update segmenttree docstrings Fixes #9943 #9975

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merged 3 commits into from
Oct 17, 2023
Merged

update segmenttree docstrings Fixes #9943 #9975

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8b1de76
update docstrings
aryandgandhi Oct 7, 2023
feaca46
update docstrings
aryandgandhi Oct 7, 2023
a725bed
update docstrings
aryandgandhi Oct 7, 2023
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41 changes: 39 additions & 2 deletions data_structures/binary_tree/segment_tree.py
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Original file line number Diff line number Diff line change
Expand Up @@ -3,29 +3,57 @@

class SegmentTree:
def __init__(self, a):
self.N = len(a)
self.A = a
self.N = len(self.A)
self.st = [0] * (
4 * self.N
) # approximate the overall size of segment tree with array N
Comment on lines 8 to 10
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@cclauss cclauss Oct 7, 2023 •
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I gotta say that overall I am not a fan of these single variable names and uppercase variable names!!!
This looks like it was literally ported from some other language with minimal modifications.

a has no data type and no self-documenting name and the class version is uppercase. If find it unreadable.

Suggested change
self.st = [0] * (
4 * self.N
) # approximate the overall size of segment tree with array N
# approximate the overall size of the segment tree with array N
self.st = [0] * (4 * self.N)

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Agreed, I'll make an issue for people to tackle naming issues in the repository, seems like it was an older thing

if self.N:
self.build(1, 0, self.N - 1)

def left(self, idx):
"""
Returns the left child index for a given index in a binary tree.

>>> s = SegmentTree([1, 2, 3])
>>> s.left(1)
2
>>> s.left(2)
4
"""
return idx * 2

def right(self, idx):
"""
Returns the right child index for a given index in a binary tree.

>>> s = SegmentTree([1, 2, 3])
>>> s.right(1)
3
>>> s.right(2)
5
"""
return idx * 2 + 1

def build(self, idx, l, r): # noqa: E741
if l == r:
self.st[idx] = A[l]
self.st[idx] = self.A[l]
else:
mid = (l + r) // 2
self.build(self.left(idx), l, mid)
self.build(self.right(idx), mid + 1, r)
self.st[idx] = max(self.st[self.left(idx)], self.st[self.right(idx)])

def update(self, a, b, val):
"""
Update the values in the segment tree in the range [a,b] with the given value.

>>> s = SegmentTree([1, 2, 3, 4, 5])
>>> s.update(2, 4, 10)
True
>>> s.query(1, 5)
10
"""
return self.update_recursive(1, 0, self.N - 1, a - 1, b - 1, val)

def update_recursive(self, idx, l, r, a, b, val): # noqa: E741
Expand All @@ -44,6 +72,15 @@ def update_recursive(self, idx, l, r, a, b, val): # noqa: E741
return True

def query(self, a, b):
"""
Query the maximum value in the range [a,b].

>>> s = SegmentTree([1, 2, 3, 4, 5])
>>> s.query(1, 3)
3
>>> s.query(1, 5)
5
"""
return self.query_recursive(1, 0, self.N - 1, a - 1, b - 1)

def query_recursive(self, idx, l, r, a, b): # noqa: E741
Expand Down