From f05cfbe00fdac1ffad783d328fa5ad3a82f62cb7 Mon Sep 17 00:00:00 2001
From: FiveMovesAhead <ying@tig.foundation>
Date: Fri, 17 Oct 2025 12:10:19 +0100
Subject: [PATCH] Submitted vehicle_routing/advanced_cw_opt

---
 .../vehicle_routing/advanced_cw_opt/README.md |  23 +
 .../vehicle_routing/advanced_cw_opt/mod.rs    | 461 ++++++++++++++++++
 tig-algorithms/src/vehicle_routing/mod.rs     |   3 +-
 3 files changed, 486 insertions(+), 1 deletion(-)
 create mode 100644 tig-algorithms/src/vehicle_routing/advanced_cw_opt/README.md
 create mode 100644 tig-algorithms/src/vehicle_routing/advanced_cw_opt/mod.rs

diff --git a/tig-algorithms/src/vehicle_routing/advanced_cw_opt/README.md b/tig-algorithms/src/vehicle_routing/advanced_cw_opt/README.md
new file mode 100644
index 0000000..6912448
--- /dev/null
+++ b/tig-algorithms/src/vehicle_routing/advanced_cw_opt/README.md
@@ -0,0 +1,23 @@
+# TIG Code Submission
+
+## Submission Details
+
+* **Challenge Name:** vehicle_routing
+* **Submission Name:** advanced_cw_opt
+* **Copyright:** 2024 syebastian
+* **Identity of Submitter:** syebastian
+* **Identity of Creator of Algorithmic Method:** null
+* **Unique Algorithm Identifier (UAI):** null
+
+## License
+
+The files in this folder are under the following licenses:
+* TIG Benchmarker Outbound License
+* TIG Commercial License
+* TIG Inbound Game License
+* TIG Innovator Outbound Game License
+* TIG Open Data License
+* TIG THV Game License
+
+Copies of the licenses can be obtained at:  
+https://github.com/tig-foundation/tig-monorepo/tree/main/docs/licenses
\ No newline at end of file
diff --git a/tig-algorithms/src/vehicle_routing/advanced_cw_opt/mod.rs b/tig-algorithms/src/vehicle_routing/advanced_cw_opt/mod.rs
new file mode 100644
index 0000000..8ef3ce3
--- /dev/null
+++ b/tig-algorithms/src/vehicle_routing/advanced_cw_opt/mod.rs
@@ -0,0 +1,461 @@
+use rand::{
+    rngs::{SmallRng, StdRng},
+    Rng, SeedableRng,
+};
+use serde_json::{Map, Value};
+use tig_challenges::vehicle_routing::*;
+
+pub fn solve_challenge(
+    challenge: &Challenge,
+    save_solution: &dyn Fn(&Solution) -> anyhow::Result<()>,
+    hyperparameters: &Option<Map<String, Value>>,
+) -> anyhow::Result<()> {
+    Err(anyhow::anyhow!("This algorithm is no longer compatible."))
+}
+
+// Old code that is no longer compatible
+#[cfg(none)]
+mod dead_code {
+    pub fn solve_challenge(
+        challenge: &Challenge,
+        save_solution: &dyn Fn(&Solution) -> anyhow::Result<()>,
+        hyperparameters: &Option<Map<String, Value>>,
+    ) -> anyhow::Result<()> {
+        let mut global_best_solution: Option<Solution> = None;
+        let mut global_best_cost = std::i32::MAX;
+
+        const NUM_ITERATIONS: usize = 200;
+
+        let num_nodes = challenge.difficulty.num_nodes;
+
+        let max_dist: f32 = challenge.distance_matrix[0].iter().sum::<i32>() as f32;
+        let p = challenge.baseline_total_distance as f32 / max_dist;
+        if p < 0.545 {
+            return Ok(());
+        }
+
+        let mut promising = false;
+
+        // Try different parameter initializations
+        for init_value in [1.0, 2.0] {
+            let mut best_solution: Option<Solution> = None;
+            let mut best_cost = std::i32::MAX;
+
+            let mut rng =
+                StdRng::seed_from_u64(u64::from_le_bytes(challenge.seed[..8].try_into().unwrap()));
+
+            let mut current_params = vec![init_value; num_nodes];
+            let mut savings_list = create_initial_savings_list(challenge);
+            recompute_and_sort_savings(&mut savings_list, &current_params, challenge);
+
+            let mut current_solution = create_solution(challenge, &current_params, &savings_list);
+            let mut current_cost =
+                calculate_solution_cost(&current_solution, &challenge.distance_matrix);
+
+            if current_cost <= challenge.baseline_total_distance {
+                let _ = save_solution(&current_solution);
+                return Ok(());
+            }
+
+            if (current_cost as f32 * 0.96) > challenge.baseline_total_distance as f32 && !promising
+            {
+                return Ok(());
+            } else {
+                promising = true;
+            }
+
+            let mut iterations_since_improvement = 0;
+            let mut stagnation_factor = 1.0;
+
+            for _ in 0..NUM_ITERATIONS {
+                let neighbor_params =
+                    generate_neighbor(&current_params, &mut rng, stagnation_factor);
+                recompute_and_sort_savings(&mut savings_list, &neighbor_params, challenge);
+
+                let mut neighbor_solution =
+                    create_solution(challenge, &neighbor_params, &savings_list);
+                postprocess_solution(
+                    &mut neighbor_solution,
+                    &challenge.distance_matrix,
+                    &challenge.demands,
+                    challenge.max_capacity,
+                );
+
+                let neighbor_cost =
+                    calculate_solution_cost(&neighbor_solution, &challenge.distance_matrix);
+
+                let delta = neighbor_cost as f32 - current_cost as f32;
+                let scaling_factor = current_cost as f32 * 0.005; // Scale based on current solution cost
+                if delta <= 0.0 {
+                    current_params = neighbor_params;
+                    current_cost = neighbor_cost;
+                    current_solution = neighbor_solution;
+                    iterations_since_improvement = 0;
+
+                    if current_cost < best_cost {
+                        best_cost = current_cost;
+                        best_solution = Some(Solution {
+                            routes: current_solution.routes.clone(),
+                        });
+                    }
+                } else if rng.gen::<f32>() < (-delta / scaling_factor).exp() {
+                    current_params = neighbor_params;
+                    iterations_since_improvement = 0;
+                } else {
+                    iterations_since_improvement += 1;
+                }
+
+                if best_cost <= challenge.baseline_total_distance {
+                    return Ok(best_solution);
+                }
+            }
+
+            if best_cost < global_best_cost {
+                global_best_cost = best_cost;
+                global_best_solution = best_solution;
+            }
+        }
+
+        Ok(global_best_solution)
+    }
+
+    #[inline]
+    fn create_initial_savings_list(challenge: &Challenge) -> Vec<(f32, u8, u8)> {
+        let num_nodes = challenge.difficulty.num_nodes;
+
+        let capacity = ((num_nodes - 1) * (num_nodes - 2)) / 2;
+        let mut savings = Vec::with_capacity(capacity);
+
+        let max_distance = challenge
+            .distance_matrix
+            .iter()
+            .flat_map(|row| row.iter())
+            .cloned()
+            .max()
+            .unwrap_or(0);
+        let threshold = max_distance / 2;
+
+        for i in 1..num_nodes {
+            for j in (i + 1)..num_nodes {
+                if challenge.distance_matrix[i][j] <= threshold {
+                    savings.push((0.0, i as u8, j as u8));
+                }
+            }
+        }
+        savings
+    }
+
+    #[inline]
+    fn recompute_and_sort_savings(
+        savings_list: &mut [(f32, u8, u8)],
+        params: &[f32],
+        challenge: &Challenge,
+    ) {
+        let distance_matrix = &challenge.distance_matrix;
+
+        // Update the score for each pair.
+        for (score, i, j) in savings_list.iter_mut() {
+            let i = *i as usize;
+            let j = *j as usize;
+            *score = (params[i] + params[j])
+                * (distance_matrix[0][i] as f32 + distance_matrix[j][0] as f32
+                    - distance_matrix[i][j] as f32);
+        }
+
+        // Sort by descending order of the score.
+        savings_list
+            .sort_unstable_by(|a, b| b.0.partial_cmp(&a.0).unwrap_or(std::cmp::Ordering::Equal));
+    }
+
+    #[inline]
+    fn generate_neighbor<R: Rng + ?Sized>(current: &[f32], rng: &mut R, k: f32) -> Vec<f32> {
+        current
+            .iter()
+            .map(|&param| {
+                let delta = rng.gen_range(-0.05 * k..=0.05 * k);
+                (param + delta).clamp(1.0, 2.0)
+            })
+            .collect()
+    }
+
+    #[inline]
+    fn calculate_solution_cost(solution: &Solution, distance_matrix: &Vec<Vec<i32>>) -> i32 {
+        solution
+            .routes
+            .iter()
+            .map(|route| {
+                route
+                    .windows(2)
+                    .map(|w| distance_matrix[w[0]][w[1]])
+                    .sum::<i32>()
+            })
+            .sum()
+    }
+
+    #[inline]
+    fn create_solution(
+        challenge: &Challenge,
+        params: &[f32],
+        savings_list: &[(f32, u8, u8)],
+    ) -> Solution {
+        let num_nodes = challenge.difficulty.num_nodes;
+        let demands = &challenge.demands;
+        let max_capacity = challenge.max_capacity;
+
+        let mut routes: Vec<Option<Vec<usize>>> = vec![None; num_nodes];
+        for i in 1..num_nodes {
+            routes[i] = Some(vec![i]);
+        }
+        let mut route_demands = demands.clone();
+
+        for &(_, i, j) in savings_list {
+            let (i, j) = (i as usize, j as usize);
+            if let (Some(left_route), Some(right_route)) = (routes[i].as_ref(), routes[j].as_ref())
+            {
+                let (left_start, left_end) =
+                    (*left_route.first().unwrap(), *left_route.last().unwrap());
+                let (right_start, right_end) =
+                    (*right_route.first().unwrap(), *right_route.last().unwrap());
+
+                // Check feasibility (same check as original).
+                if left_start == right_start
+                    || route_demands[left_start] + route_demands[right_start] > max_capacity
+                {
+                    continue;
+                }
+
+                let mut new_route = routes[i].take().unwrap();
+                let mut right_route = routes[j].take().unwrap();
+
+                // Reverse if needed (same as original).
+                if left_start == i {
+                    new_route.reverse();
+                }
+                if right_end == j {
+                    right_route.reverse();
+                }
+
+                new_route.extend(right_route);
+
+                let combined_demand = route_demands[left_start] + route_demands[right_start];
+                let new_start = new_route[0];
+                let new_end = *new_route.last().unwrap();
+
+                route_demands[new_start] = combined_demand;
+                route_demands[new_end] = combined_demand;
+
+                routes[new_start] = Some(new_route.clone());
+                routes[new_end] = Some(new_route);
+            }
+        }
+
+        // Wrap each route with depot (0) at start and end.
+        Solution {
+            routes: routes
+                .into_iter()
+                .enumerate()
+                .filter_map(|(i, route)| {
+                    route.filter(|r| r[0] == i) // only keep the "canonical" copy
+                })
+                .map(|mut route| {
+                    route.insert(0, 0);
+                    route.push(0);
+                    route
+                })
+                .collect(),
+        }
+    }
+
+    pub fn postprocess_solution(
+        solution: &mut Solution,
+        distance_matrix: &Vec<Vec<i32>>,
+        demands: &Vec<i32>,
+        max_capacity: i32,
+    ) {
+        loop {
+            let intra_improved = two_opt_all_routes(solution, distance_matrix);
+            let inter_route_improved = unsafe {
+                try_inter_route_swap_unsafe(solution, distance_matrix, demands, max_capacity)
+            };
+            if !intra_improved && !inter_route_improved {
+                break;
+            }
+        }
+    }
+
+    #[inline]
+    fn two_opt_all_routes(solution: &mut Solution, distance_matrix: &Vec<Vec<i32>>) -> bool {
+        let mut improved = false;
+        for route in &mut solution.routes {
+            if unsafe { two_opt_unsafe(route, distance_matrix) } {
+                improved = true;
+            }
+        }
+        improved
+    }
+
+    #[inline]
+    unsafe fn two_opt_unsafe(route: &mut Vec<usize>, distance_matrix: &Vec<Vec<i32>>) -> bool {
+        let n = route.len();
+        if n < 4 {
+            return false;
+        }
+
+        let mut improved = false;
+        let route_ptr = route.as_mut_ptr();
+
+        for i in 1..(n - 2) {
+            let mut best_gain = 0;
+            let mut best_j = 0;
+
+            for j in (i + 1)..(n - 1) {
+                let [r_im1, r_i, r_j, r_jp1] = [
+                    *route_ptr.add(i - 1),
+                    *route_ptr.add(i),
+                    *route_ptr.add(j),
+                    *route_ptr.add(j + 1),
+                ];
+
+                let gain = distance_matrix[r_im1][r_i] + distance_matrix[r_j][r_jp1]
+                    - distance_matrix[r_im1][r_j]
+                    - distance_matrix[r_i][r_jp1];
+
+                if gain > best_gain {
+                    best_gain = gain;
+                    best_j = j;
+                }
+            }
+
+            if best_gain > 0 {
+                let mut start = i;
+                let mut end = best_j;
+                while start < end {
+                    let tmp = *route_ptr.add(start);
+                    *route_ptr.add(start) = *route_ptr.add(end);
+                    *route_ptr.add(end) = tmp;
+                    start += 1;
+                    end -= 1;
+                }
+                improved = true;
+            }
+        }
+        improved
+    }
+    #[inline]
+    unsafe fn try_inter_route_swap_unsafe(
+        solution: &mut Solution,
+        distance_matrix: &Vec<Vec<i32>>,
+        demands: &Vec<i32>,
+        max_capacity: i32,
+    ) -> bool {
+        let mut improved = false;
+        let num_routes = solution.routes.len();
+        let routes_ptr = solution.routes.as_mut_ptr();
+
+        // Store all possible improvements: (improvement, route_i_idx, route_j_idx, new_route_i, new_route_j)
+        let mut all_improvements = Vec::new();
+
+        for i in 0..num_routes {
+            for j in (i + 1)..num_routes {
+                let route_i = &mut *routes_ptr.add(i);
+                let route_j = &mut *routes_ptr.add(j);
+
+                if let Some((improvement, new_route_i, new_route_j)) =
+                    unsafe_find_best_swap_with_value(
+                        route_i,
+                        route_j,
+                        distance_matrix,
+                        demands,
+                        max_capacity,
+                    )
+                {
+                    all_improvements.push((improvement, i, j, new_route_i, new_route_j));
+                }
+            }
+        }
+
+        // Sort improvements by descending order of improvement value
+        all_improvements.sort_unstable_by(|a, b| b.0.cmp(&a.0));
+
+        // Keep track of which routes have been modified
+        let mut modified_routes = vec![false; num_routes];
+
+        // Apply non-conflicting improvements
+        for (_, route_i_idx, route_j_idx, new_route_i, new_route_j) in all_improvements {
+            // Skip if either route has already been modified
+            if modified_routes[route_i_idx] || modified_routes[route_j_idx] {
+                continue;
+            }
+
+            // Apply the swap
+            let route_i = &mut *routes_ptr.add(route_i_idx);
+            let route_j = &mut *routes_ptr.add(route_j_idx);
+            *route_i = new_route_i;
+            *route_j = new_route_j;
+
+            // Mark both routes as modified
+            modified_routes[route_i_idx] = true;
+            modified_routes[route_j_idx] = true;
+            improved = true;
+        }
+
+        improved
+    }
+
+    #[inline]
+    unsafe fn unsafe_find_best_swap_with_value(
+        route1: &Vec<usize>,
+        route2: &Vec<usize>,
+        distance_matrix: &Vec<Vec<i32>>,
+        demands: &Vec<i32>,
+        max_capacity: i32,
+    ) -> Option<(i32, Vec<usize>, Vec<usize>)> {
+        let mut best_improvement = 0;
+        let mut best_swap = None;
+
+        let r1_ptr = route1.as_ptr();
+        let r2_ptr = route2.as_ptr();
+        let r1_len = route1.len();
+        let r2_len = route2.len();
+
+        let route1_demand: i32 = route1.iter().map(|&n| demands[n]).sum();
+        let route2_demand: i32 = route2.iter().map(|&n| demands[n]).sum();
+
+        for i in 1..(r1_len - 1) {
+            for j in 1..(r2_len - 1) {
+                let [r1_im1, r1_i, r1_ip1] =
+                    [*r1_ptr.add(i - 1), *r1_ptr.add(i), *r1_ptr.add(i + 1)];
+
+                let [r2_jm1, r2_j, r2_jp1] =
+                    [*r2_ptr.add(j - 1), *r2_ptr.add(j), *r2_ptr.add(j + 1)];
+
+                let demand_delta = demands[r2_j] - demands[r1_i];
+
+                if route1_demand + demand_delta > max_capacity
+                    || route2_demand - demand_delta > max_capacity
+                {
+                    continue;
+                }
+
+                let improvement = distance_matrix[r1_im1][r1_i]
+                    + distance_matrix[r1_i][r1_ip1]
+                    + distance_matrix[r2_jm1][r2_j]
+                    + distance_matrix[r2_j][r2_jp1]
+                    - distance_matrix[r1_im1][r2_j]
+                    - distance_matrix[r2_j][r1_ip1]
+                    - distance_matrix[r2_jm1][r1_i]
+                    - distance_matrix[r1_i][r2_jp1];
+
+                if improvement > best_improvement {
+                    best_improvement = improvement;
+                    let mut new_route1 = route1.clone();
+                    let mut new_route2 = route2.clone();
+                    new_route1[i] = r2_j;
+                    new_route2[j] = r1_i;
+                    best_swap = Some((improvement, new_route1, new_route2));
+                }
+            }
+        }
+        best_swap
+    }
+}
diff --git a/tig-algorithms/src/vehicle_routing/mod.rs b/tig-algorithms/src/vehicle_routing/mod.rs
index 930b4fb..6c85b13 100644
--- a/tig-algorithms/src/vehicle_routing/mod.rs
+++ b/tig-algorithms/src/vehicle_routing/mod.rs
@@ -114,7 +114,8 @@
 
 // c002_a058
 
-// c002_a059
+pub mod advanced_cw_opt;
+pub use advanced_cw_opt as c002_a059;
 
 // c002_a060