From a880c1b3954633e249d70ce5531f4f47093da939 Mon Sep 17 00:00:00 2001
From: Rutherther <rutherther@ditigal.xyz>
Date: Mon, 27 Oct 2025 20:45:53 +0100
Subject: [PATCH] feat: add best replacement

---
 codes/eoa_lib/src/replacement.rs | 58 ++++++++++++++++++++++++++++++--
 1 file changed, 55 insertions(+), 3 deletions(-)

diff --git a/codes/eoa_lib/src/replacement.rs b/codes/eoa_lib/src/replacement.rs
index 3c79db67e44370ae69ce61d95a67e61a0e671bcb..c6dfb20fe6e3cae488e217de8537e65db8864b6f 100644
--- a/codes/eoa_lib/src/replacement.rs
+++ b/codes/eoa_lib/src/replacement.rs
@@ -1,19 +1,34 @@
 use rand::{seq::IteratorRandom, RngCore};
+use std::fmt::Debug;
 
 use crate::{comparison::BetterThanOperator, fitness::FitnessFunction, selection::{Selection, TournamentSelection}};
 
-#[derive(Clone)]
+fn extract_by_indices<T>(mut x: Vec<T>, mut idxs: Vec<usize>) -> Vec<T> {
+    idxs.sort_unstable_by(|a, b| b.cmp(a));
+
+    let mut result = Vec::with_capacity(idxs.len());
+    for idx in idxs {
+        if idx < x.len() {
+            result.push(x.swap_remove(idx));
+        }
+    }
+
+    result.reverse();
+    result
+}
+
+#[derive(Clone, Debug)]
 pub struct Population<TChromosome> {
     population: Vec<TChromosome>
 }
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub struct EvaluatedChromosome<TChromosome, TResult> {
     pub chromosome: TChromosome,
     pub evaluation: TResult,
 }
 
-#[derive(Clone)]
+#[derive(Clone, Debug)]
 pub struct EvaluatedPopulation<TChromosome, TResult> {
     pub population: Vec<EvaluatedChromosome<TChromosome, TResult>>
 }
@@ -25,6 +40,10 @@ impl<TChromosome> Population<TChromosome> {
         }
     }
 
+    pub fn from_iterator(iter: impl Iterator<Item = TChromosome>) -> Self {
+        Self::from_vec(iter.collect())
+    }
+
     pub fn evaluate<T: FitnessFunction<In = TChromosome>>(self, func: &T) -> Result<EvaluatedPopulation<TChromosome, T::Out>, T::Err> {
         EvaluatedPopulation::evaluate(
             self.population,
@@ -122,6 +141,39 @@ pub trait Replacement<TChromosome, TResult> {
     ) -> EvaluatedPopulation<TChromosome, TResult>;
 }
 
+pub struct BestReplacement;
+impl BestReplacement {
+    pub fn new() -> Self {
+        Self
+    }
+}
+
+impl<TChromosome, TResult: Copy + Debug> Replacement<TChromosome, TResult> for BestReplacement {
+    fn replace(
+        &mut self,
+        parents_evaluations: EvaluatedPopulation<TChromosome, TResult>,
+        offsprings_evaluations: EvaluatedPopulation<TChromosome, TResult>,
+        better_than: &dyn BetterThanOperator<TResult>
+    ) -> EvaluatedPopulation<TChromosome, TResult> {
+        let count = parents_evaluations.population.len();
+        let mut population = parents_evaluations;
+        population.join(offsprings_evaluations);
+
+        let mut idxs = (0..population.population.len())
+            .collect::<Vec<_>>();
+        idxs.sort_unstable_by(|&i, &j| better_than.ordering(
+            &population.population[i].evaluation,
+            &population.population[j].evaluation)
+        );
+
+        idxs.truncate(count);
+
+        EvaluatedPopulation::from_vec(
+            extract_by_indices(population.deconstruct(), idxs)
+        )
+    }
+}
+
 pub struct GenerationalReplacement;
 impl<TInput, TResult> Replacement<TInput, TResult> for GenerationalReplacement {
     fn replace(