From 88a33d4a727e92fdd404092d07697f24c6da5ee2 Mon Sep 17 00:00:00 2001
From: Andrew Golovashevich <landgrafhomyak@gmail.com>
Date: Sun, 8 Feb 2026 07:38:24 +0300
Subject: [PATCH] [lab3] Ant algorithm simulation

---
 lab3/src/algo/edges.rs |  43 ++++++++++++++++
 lab3/src/algo/mod.rs   |   4 ++
 lab3/src/algo/state.rs | 109 +++++++++++++++++++++++++++++++++++++++++
 3 files changed, 156 insertions(+)
 create mode 100644 lab3/src/algo/edges.rs
 create mode 100644 lab3/src/algo/mod.rs
 create mode 100644 lab3/src/algo/state.rs

diff --git a/lab3/src/algo/edges.rs b/lab3/src/algo/edges.rs
new file mode 100644
index 0000000..732bfbb
--- /dev/null
+++ b/lab3/src/algo/edges.rs
@@ -0,0 +1,43 @@
+use std::ops::{Index, IndexMut};
+
+pub struct Edge {
+    pub vertex1_index: usize,
+    pub vertex2_index: usize,
+    pub length: f64,
+    pub ferment_intensity: f64,
+}
+
+enum EdgeCell {
+    Free { next_free_cell_id: Option<usize> },
+    Value { data: Edge },
+}
+
+pub struct EdgesVec {
+    storage: Vec<EdgeCell>,
+}
+
+impl EdgesVec {}
+
+impl Index<usize> for EdgesVec {
+    type Output = Edge;
+
+    fn index(&self, index: usize) -> &Self::Output {
+        match self.storage.get(index).expect("Edge index out of bounds") {
+            EdgeCell::Free { .. } => panic!("Referenced edge doesn't exists"),
+            EdgeCell::Value { data } => return data,
+        }
+    }
+}
+
+impl IndexMut<usize> for EdgesVec {
+    fn index_mut(&mut self, index: usize) -> &mut Self::Output {
+        match self
+            .storage
+            .get_mut(index)
+            .expect("Edge index out of bounds")
+        {
+            EdgeCell::Free { .. } => panic!("Referenced edge doesn't exists"),
+            EdgeCell::Value { data } => return data,
+        }
+    }
+}
diff --git a/lab3/src/algo/mod.rs b/lab3/src/algo/mod.rs
new file mode 100644
index 0000000..b280f2d
--- /dev/null
+++ b/lab3/src/algo/mod.rs
@@ -0,0 +1,4 @@
+mod edges;
+mod state;
+
+pub use edges::EdgesVec;
\ No newline at end of file
diff --git a/lab3/src/algo/state.rs b/lab3/src/algo/state.rs
new file mode 100644
index 0000000..9eb6a67
--- /dev/null
+++ b/lab3/src/algo/state.rs
@@ -0,0 +1,109 @@
+use crate::algo::EdgesVec;
+use std::collections::HashSet;
+use std::ops::Mul;
+
+#[derive(Clone, Copy)]
+pub enum AntDirection {
+    ToSecond,
+    ToFirst,
+}
+
+pub struct Ant {
+    allowed_vertices: HashSet<usize>,
+    location: AntLocation,
+}
+
+pub enum AntLocation {
+    OnEdge {
+        edge_index: usize,
+        offset: u16,
+        direction: AntDirection,
+    },
+    OnVertex {
+        vertex_index: usize,
+    },
+}
+
+pub struct AntsSimulationState<'a, Rng: rand::Rng> {
+    rng: Rng,
+    vertices: &'a Vec<HashSet<usize>>,
+    edges: &'a mut EdgesVec,
+    ants: &'a mut [Ant],
+}
+
+pub fn updateState<Rng: rand::Rng>(
+    state: &mut AntsSimulationState<Rng>,
+    ferment_weight: f64,
+    heuristic_coefficient: f64,
+    q: f64,
+    r: f64,
+    speed: u16,
+) -> bool {
+    let mut finished_ants_count = 0usize;
+    for ant in state.ants.iter_mut() {
+        match &mut ant.location {
+            AntLocation::OnEdge {
+                edge_index,
+                offset,
+                direction,
+            } => match offset.checked_add(speed) {
+                Some(newOffset) => *offset = newOffset,
+                None => {
+                    let edge = &mut state.edges[*edge_index];
+                    edge.ferment_intensity += (q / edge.length) * r;
+                    let vertex_index;
+                    match direction {
+                        AntDirection::ToSecond => vertex_index = edge.vertex2_index,
+                        AntDirection::ToFirst => vertex_index = edge.vertex1_index,
+                    }
+                    ant.location = AntLocation::OnVertex { vertex_index }
+                }
+            },
+            AntLocation::OnVertex { vertex_index } => {
+                let allowed_outbounds = state.vertices[*vertex_index]
+                    .iter()
+                    .map(|ei| (*ei, &state.edges[*ei]))
+                    .map(|(ei, e)| {
+                        if *vertex_index == e.vertex1_index {
+                            return (ei, e, e.vertex2_index, AntDirection::ToSecond);
+                        } else {
+                            return (ei, e, e.vertex1_index, AntDirection::ToFirst);
+                        }
+                    })
+                    .filter(|e| ant.allowed_vertices.contains(&e.2))
+                    .map(|e| {
+                        return (
+                            e.0,
+                            (e.2, e.3),
+                            e.1.ferment_intensity.powf(ferment_weight)
+                                * (1.0 / e.1.length).powf(heuristic_coefficient),
+                        );
+                    })
+                    .collect::<Vec<(usize, (usize, AntDirection), f64)>>();
+
+                let mut accumulator: f64 = allowed_outbounds
+                    .iter()
+                    .fold(0.0, |a, e| a + e.2)
+                    .mul(state.rng.random::<f64>());
+                let target_vertex_index = allowed_outbounds.iter().find(|e| {
+                    accumulator -= e.2;
+                    return accumulator <= 0.0;
+                });
+
+                match target_vertex_index {
+                    None => finished_ants_count += 1,
+                    Some((ei, (vi, dir), _)) => {
+                        ant.allowed_vertices.remove(vi);
+                        ant.location = AntLocation::OnEdge {
+                            edge_index: *ei,
+                            offset: 0,
+                            direction: *dir
+                        }
+                    }
+                };
+            }
+        }
+    }
+
+    return finished_ants_count == state.ants.len()
+}