Submitted vehicle_routing/cw_heuristic

tig-algorithms/src/vehicle_routing/cw_heuristic/README.md

@@ -0,0 +1,23 @@
+# TIG Code Submission
+
+## Submission Details
+
+* **Challenge Name:** vehicle_routing
+* **Algorithm Name:** cw_heuristic
+* **Copyright:** 2024 Just
+* **Identity of Submitter:** Just
+* **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

tig-algorithms/src/vehicle_routing/cw_heuristic/mod.rs

@@ -0,0 +1,131 @@
+use anyhow::{anyhow, Result};
+use serde_json::{Map, Value};
+use tig_challenges::vehicle_routing::*;
+
+
+pub fn solve_challenge(
+    challenge: &Challenge,
+    save_solution: &dyn Fn(&Solution) -> Result<()>,
+    hyperparameters: &Option<Map<String, Value>>,
+) -> Result<()> {
+    Err(anyhow!("This algorithm is no longer compatible."))
+}
+
+// Old code that is no longer compatible
+#[cfg(none)]
+mod dead_code {
+    use tig_challenges::vehicle_routing::*;
+
+
+    pub fn solve_challenge(challenge: &Challenge) -> anyhow::Result<Option<Solution>> {
+        let mut solution = Solution {
+            sub_solutions: Vec::new(),
+        };
+        for sub_instance in &challenge.sub_instances {
+            match solve_sub_instance(sub_instance)? {
+                Some(sub_solution) => solution.sub_solutions.push(sub_solution),
+                None => return Ok(None),
+            }
+        }
+        Ok(Some(solution))
+    }
+
+    pub fn solve_sub_instance(challenge: &SubInstance) -> anyhow::Result<Option<SubSolution>> {
+        let d = &challenge.distance_matrix;
+        let c = challenge.max_capacity;
+        let n = challenge.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 < 0.57 {
+            return Ok(None)
+        }
+
+        // Clarke-Wright heuristic for node pairs based on their distances to depot
+        // vs distance between each other
+        let mut scores: Vec<(i32, usize, usize)> = Vec::with_capacity((n-1)*(n-2)/2);
+        for i in 1..n {
+            for j in (i + 1)..n {
+                scores.push((d[i][0] + d[0][j] - d[i][j], i, j));
+            }
+        }
+
+        scores.sort_unstable_by(|a, b| b.0.cmp(&a.0));    
+    
+        // Create a route for every node
+        let mut routes: Vec<Option<Vec<usize>>> = (0..n).map(|i| Some(vec![i])).collect();
+        routes[0] = None;
+        let mut route_demands: Vec<i32> = challenge.demands.clone();
+   
+        // Iterate through node pairs, starting from greatest score
+        for (s, i, j) in scores {
+            // Stop if score is negative
+            if s < 0 {
+                break;
+            }
+
+            // Skip if joining the nodes is not possible
+            if routes[i].is_none() || routes[j].is_none() {
+                continue;
+            }
+
+            let left_route = routes[i].as_ref().unwrap();
+            let right_route = routes[j].as_ref().unwrap();
+            let mut left_startnode = left_route[0];
+            let right_startnode = right_route[0];
+            let left_endnode = left_route[left_route.len() - 1];
+            let mut right_endnode = right_route[right_route.len() - 1];
+            let merged_demand = route_demands[left_startnode] + route_demands[right_startnode];
+
+            if left_startnode == right_startnode || merged_demand > c {
+                continue;
+            }
+
+            let mut left_route = routes[i].take().unwrap();
+            let mut right_route = routes[j].take().unwrap();
+            routes[left_startnode] = None;
+            routes[right_startnode] = None;
+            routes[left_endnode] = None;
+            routes[right_endnode] = None;
+
+            // reverse it
+            if left_startnode == i {
+                left_route.reverse();
+                left_startnode = left_endnode;
+            }
+            if right_endnode == j {
+                right_route.reverse();
+                right_endnode = right_startnode;
+            }
+
+            let mut new_route = left_route;
+            new_route.extend(right_route);
+
+            // Only the start and end nodes of routes are kept
+            routes[left_startnode] = Some(new_route.clone());
+            routes[right_endnode] = Some(new_route);
+            route_demands[left_startnode] = merged_demand;
+            route_demands[right_endnode] = merged_demand;
+        }
+    
+        let routes = routes
+        .into_iter()
+        .enumerate()
+        .filter(|(i, x)| x.as_ref().is_some_and(|x| x[0] == *i))
+        .map(|(_, mut x)| {
+            let mut route = vec![0];
+            route.append(x.as_mut().unwrap());
+            route.push(0);
+            route
+        })
+        .collect();
+
+        Ok(Some(SubSolution {
+            routes
+        }))
+    }
+}
+
+pub fn help() {
+    println!("No help information available.");
+}

tig-algorithms/src/vehicle_routing/mod.rs

@@ -66,7 +66,8 @@
 
 // c002_a034
 
-// c002_a035
+pub mod cw_heuristic;
+pub use cw_heuristic as c002_a035;
 
 // c002_a036