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introduce k as the amount of elements in a chunk

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jacekpoz 2024-05-06 23:11:16 +02:00
parent f90c5b2b26
commit 1059dfecb3
Signed by: poz
SSH key fingerprint: SHA256:JyLeVWE4bF3tDnFeUpUaJsPsNlJyBldDGV/dIKSLyN8
1 changed files with 12 additions and 8 deletions
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20
libselect/src/normal_select.rs
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@ -42,7 +42,7 @@ impl NormalSelect {
j j
} }
fn _select(&mut self, list: &mut Vec<u64>, lo: usize, hi: usize, k: usize) -> (usize, u64) { fn _select(&mut self, list: &mut Vec<u64>, lo: usize, hi: usize, ord_stat: usize, k: usize) -> (usize, u64) {
if lo == hi { if lo == hi {
return (lo, list[lo]); return (lo, list[lo]);
} }
@ -50,7 +50,7 @@ impl NormalSelect {
if self.should_print { println!("list: {:?}; lo: {lo}; hi: {hi}", list); } if self.should_print { println!("list: {:?}; lo: {lo}; hi: {hi}", list); }
let mut medians: Vec<u64> = vec![]; let mut medians: Vec<u64> = vec![];
let mut chunks = list.chunks(5) let mut chunks = list.chunks(k)
.collect::<Vec<_>>(); .collect::<Vec<_>>();
for mut chunk in chunks.iter_mut().map(|c| c.to_vec()) { for mut chunk in chunks.iter_mut().map(|c| c.to_vec()) {
@ -66,20 +66,24 @@ impl NormalSelect {
let n = hi - lo; let n = hi - lo;
let (pivot, _) = self._select(&mut medians, 0, n.div_ceil(5) - 1, (n.div_ceil(5) - 1).div_ceil(2)); let (pivot, _) = self._select(&mut medians, 0, n.div_ceil(k) - 1, (n.div_ceil(k) - 1).div_ceil(2), k);
if self.should_print { println!("pivot: {pivot}"); } if self.should_print { println!("pivot: {pivot}"); }
let r = self.partition(list, lo, hi, pivot); let r = self.partition(list, lo, hi, pivot);
if self.should_print { println!("r: {r}"); } if self.should_print { println!("r: {r}"); }
let i = r - lo + 1; let i = r - lo + 1;
if i == k { if i == ord_stat {
return (r, list[r]); return (r, list[r]);
} else if i < k { } else if i < ord_stat {
return self._select(list, r + 1, hi, k - i); return self._select(list, r + 1, hi, ord_stat - i, k);
} else { } else {
return self._select(list, lo, r - 1, k); return self._select(list, lo, r - 1, ord_stat, k);
} }
} }
pub fn select_k(&mut self, list: &mut Vec<u64>, order_statistic: usize, k: usize) -> u64 {
self._select(list, 0, list.len() - 1, order_statistic, k).1
}
} }
impl Select for NormalSelect { impl Select for NormalSelect {
@ -93,7 +97,7 @@ impl Select for NormalSelect {
} }
fn select_mut(&mut self, list: &mut Vec<u64>, order_statistic: usize) -> u64 { fn select_mut(&mut self, list: &mut Vec<u64>, order_statistic: usize) -> u64 {
self._select(list, 0, list.len() - 1, order_statistic).1 self.select_k(list, order_statistic, 5)
} }
fn num_comp(&self) -> u64 { fn num_comp(&self) -> u64 {