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Segtree: Monoid BitwiseOr/BitwiseAnd/BitwiseXor, get_slice #115

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merged 3 commits into from
Apr 16, 2023

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@mizar mizar commented Jan 25, 2023

  • Monoid BitOrOper/BitAndOper/BitXorOper: for bool/bitset type segtree data
  • FromIterator: struct from Iterator
  • get_slice: allows slice access to internal data

usage sample: ABC285F - Substring of Sorted String
https://atcoder.jp/contests/abc285/submissions/38317831

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mizar commented Jan 25, 2023

The following code keeps the segtree implementation, but changes the input/output processing.
https://atcoder.jp/contests/abc285/submissions/38318119

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mizar commented Mar 27, 2023

For the FromIterator, the following PR exists, so I'll just Revert it here
#107

src/segtree.rs Outdated
@@ -68,6 +68,48 @@ where
}
}

pub struct BitOrOper<S>(Infallible, PhantomData<fn() -> S>);
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This is just a matter of preference, but I prefer BitwiseOr. ("Operation" is obvious in the context, while "bit or" is kinda misleading (are we handling a single bit?))

src/segtree.rs Outdated
@@ -107,6 +149,10 @@ impl<M: Monoid> Segtree<M> {
self.d[p + self.size].clone()
}

pub fn get_slice(&self) -> &[M::S] {
&self.d[self.size..(self.size + self.n)]
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Just showing off a trick: did you know that you can write like this 😜? (I prefer this style becuase you need to specify the same variable twice.)

Suggested change
&self.d[self.size..(self.size + self.n)]
&self.d[self.size..][..self.n]

src/segtree.rs Outdated
{
type S = S;
fn identity() -> Self::S {
S::default()
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I'm still doubting if we should use "Default" in this case, considering the semantics. (See also my previous comment).

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LGTM

@TonalidadeHidrica TonalidadeHidrica changed the title Segtree: Monoid BitOrOper/BitAndOper/BitXorOper, FromIterator, get_slice Segtree: Monoid BitwiseOr/BitwiseAnd/BitwiseXor, get_slice Apr 16, 2023
@TonalidadeHidrica TonalidadeHidrica merged commit 33dc514 into rust-lang-ja:master Apr 16, 2023
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@mizar mizar deleted the segtree branch April 16, 2023 22:36
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2 participants