From ec7345a58c11d82038bf20c41484c27f07f3e4dc Mon Sep 17 00:00:00 2001
From: Rutherther <rutherther@ditigal.xyz>
Date: Sat, 1 Nov 2025 10:23:03 +0100
Subject: [PATCH] feat(lib): add n consecutive bit flip perturbation for binary
 string

---
 codes/eoa_lib/src/perturbation/mod.rs | 32 ++++++++++++++++++++++++++-
 1 file changed, 31 insertions(+), 1 deletion(-)

diff --git a/codes/eoa_lib/src/perturbation/mod.rs b/codes/eoa_lib/src/perturbation/mod.rs
index 513432684c8b5d672f494050991b27c474ac8490..d8d9dd9429293f6aeca137f64db96d01133019b0 100644
--- a/codes/eoa_lib/src/perturbation/mod.rs
+++ b/codes/eoa_lib/src/perturbation/mod.rs
@@ -62,7 +62,7 @@ impl<TChromosome: 'static> PerturbationOperator for IdentityPerturbation<TChromo
 }
 
 pub struct BinaryStringBitPerturbation<D> {
-    p: f64,
+    pub p: f64,
     _phantom: PhantomData<D>
 }
 
@@ -139,6 +139,36 @@ where
     }
 }
 
+pub struct BinaryStringFlipNPerturbation<D> {
+    n: usize,
+    _phantom: PhantomData<D>,
+}
+
+impl<D> BinaryStringFlipNPerturbation<D> {
+    pub fn new(n: usize) -> Self {
+        Self {
+            n,
+            _phantom: PhantomData
+        }
+    }
+}
+
+impl<D> PerturbationOperator for BinaryStringFlipNPerturbation<D>
+where
+    D: Dim,
+    DefaultAllocator: Allocator<D>
+{
+    type Chromosome = BinaryString<D>;
+
+    fn perturb(&self, chromosome: &mut Self::Chromosome, rng: &mut dyn RngCore) {
+        let index = rng.random_range(0..chromosome.vec.len());
+
+        for i in index..(index + self.n).min(chromosome.vec.len()) {
+            chromosome.vec[i] = 1 - chromosome.vec[i];
+        }
+    }
+}
+
 pub struct RandomDistributionPerturbation<const LEN: usize, TDistribution: Distribution<f64>> {
     distribution: TDistribution,
     parameter: f64