From 381091456ff37887e03f4a75f69304ffbeddb0e3 Mon Sep 17 00:00:00 2001
From: Rutherther <rutherther@ditigal.xyz>
Date: Tue, 28 Oct 2025 21:27:19 +0100
Subject: [PATCH] feat: add loading of optimal cost from solutions.txt

---
 codes/tsp_hw01/src/main.rs | 40 ++++++++++++++++++++++++++++++++++++--
 1 file changed, 38 insertions(+), 2 deletions(-)

diff --git a/codes/tsp_hw01/src/main.rs b/codes/tsp_hw01/src/main.rs
index 62984b3592da7bc81b4e950d8cc93da8529ceb89..5c3ddb73731776ed150a15df693647887aeb0f54 100644
--- a/codes/tsp_hw01/src/main.rs
+++ b/codes/tsp_hw01/src/main.rs
@@ -2,7 +2,7 @@ pub mod tsp;
 pub mod graph;
 
 use tsp::{TSPInstance, TSPRandomInitializer, SwapPerturbation};
-use nalgebra::{Const, Dyn};
+use nalgebra::{Const, Dim, Dyn};
 use eoa_lib::{
     initializer::Initializer,
     local_search::local_search_first_improving,
@@ -56,10 +56,43 @@ fn load_tsp_instance(filename: &str) -> Result<TSPInstance<Dyn>, Box<dyn std::er
     Ok(TSPInstance::new_dyn(cities))
 }
 
+fn load_optimal_cost(instance_filename: &str) -> Result<f64, Box<dyn std::error::Error>> {
+    let instance_name = std::path::Path::new(instance_filename)
+        .file_stem()
+        .and_then(|s| s.to_str())
+        .ok_or("Could not extract instance name")?
+        .trim_end_matches(".tsp");
+
+    let solutions_path = std::path::Path::new(instance_filename)
+        .parent()
+        .unwrap_or_else(|| std::path::Path::new("."))
+        .join("solutions.txt");
+
+    let content = std::fs::read_to_string(solutions_path)?;
+
+    for line in content.lines() {
+        let line = line.trim();
+        if let Some(colon_pos) = line.find(':') {
+            let name = line[..colon_pos].trim();
+            if name == instance_name {
+                let cost_str = line[colon_pos + 1..].trim();
+                return cost_str.parse::<f64>()
+                    .map_err(|e| format!("Could not parse cost '{}': {}", cost_str, e).into());
+            }
+        }
+    }
+
+    Err(format!("Optimal cost not found for instance '{}'", instance_name).into())
+}
+
 fn main() -> Result<(), Box<dyn std::error::Error>> {
     // Load a TSP instance from file
-    let instance = load_tsp_instance("instances/berlin52.tsp.gz")?;
+    let filename = "instances/berlin52.tsp.gz";
+    let instance = load_tsp_instance(filename)?;
     let dimension = instance.dimension();
+    let optimal_cost = load_optimal_cost(filename)?;
+
+    println!("Loaded {} with {} cities (optimal cost: {})", filename, dimension.value(), optimal_cost);
 
     // Plot just the instance
     instance.plot("tsp_instance.png")?;
@@ -95,6 +128,9 @@ fn main() -> Result<(), Box<dyn std::error::Error>> {
         instance.solution_cost(&initial_solution),
         result.best_candidate.fit,
         result.cycles);
+    println!("Gap to optimal: {:.2} ({:.1}%)",
+        result.best_candidate.fit - optimal_cost,
+        ((result.best_candidate.fit - optimal_cost) / optimal_cost) * 100.0);
 
     Ok(())
 }