diff --git a/src/graph.cpp b/src/graph.cpp
index 11d319e..65c3942 100644
--- a/src/graph.cpp
+++ b/src/graph.cpp
@@ -17,7 +17,7 @@ void Graph::add_edge(int source, int target, int weight) {
     adjList[target].emplace_back(source, weight);
 }
 
-// Trouver le chemin le plus court entre deux nœuds
+// Trouver le chemin le plus court entre deux nœuds avec une optimisation bidirectionnelle
 std::vector<int> Graph::shortest_path(int source, int target, int& totalTime) {
     constexpr int INF = std::numeric_limits<int>::max();
 
@@ -29,6 +29,7 @@ std::vector<int> Graph::shortest_path(int source, int target, int& totalTime) {
     size_t n = adjList.size();
     std::vector<int> distForward(n, INF), distBackward(n, INF);
     std::vector<int> prevForward(n, -1), prevBackward(n, -1);
+    std::vector<bool> processedForward(n, false), processedBackward(n, false);
 
     distForward[source] = 0;
     distBackward[target] = 0;
@@ -47,26 +48,30 @@ std::vector<int> Graph::shortest_path(int source, int target, int& totalTime) {
     int bestCost = INF;
     int meetingNode = -1;
 
-    // Process nodes alternately in forward and backward directions
-    while (!pqForward.empty() && !pqBackward.empty()) {
-        // Expand forward
+    // Processus bidirectionnel
+    while (!pqForward.empty() || !pqBackward.empty()) {
+        // Expansion dans la direction avant
         if (!pqForward.empty()) {
-            auto [currentF, current] = pqForward.top();
+            auto [currentDistF, currentNodeF] = pqForward.top();
             pqForward.pop();
 
-            if (currentF > distForward[current]) continue;
+            if (processedForward[currentNodeF]) continue;
+            processedForward[currentNodeF] = true;
 
-            for (const Edge& edge : adjList[current]) {
+            for (const Edge& edge : adjList[currentNodeF]) {
                 int neighbor = edge.target;
-                int newDist = distForward[current] + edge.weight;
+                int newDist = distForward[currentNodeF] + edge.weight;
 
                 if (newDist < distForward[neighbor]) {
                     distForward[neighbor] = newDist;
-                    prevForward[neighbor] = current;
-                    pqForward.emplace(newDist, neighbor);
+                    prevForward[neighbor] = currentNodeF;
+
+                    if (!processedForward[neighbor]) {
+                        pqForward.emplace(newDist, neighbor);
+                    }
                 }
 
-                if (distBackward[neighbor] < INF) {
+                if (processedBackward[neighbor]) {
                     int potentialCost = distForward[neighbor] + distBackward[neighbor];
                     if (potentialCost < bestCost) {
                         bestCost = potentialCost;
@@ -76,24 +81,28 @@ std::vector<int> Graph::shortest_path(int source, int target, int& totalTime) {
             }
         }
 
-        // Expand backward
+        // Expansion dans la direction arrière
         if (!pqBackward.empty()) {
-            auto [currentB, currentBack] = pqBackward.top();
+            auto [currentDistB, currentNodeB] = pqBackward.top();
             pqBackward.pop();
 
-            if (currentB > distBackward[currentBack]) continue;
+            if (processedBackward[currentNodeB]) continue;
+            processedBackward[currentNodeB] = true;
 
-            for (const Edge& edge : adjList[currentBack]) {
+            for (const Edge& edge : adjList[currentNodeB]) {
                 int neighbor = edge.target;
-                int newDist = distBackward[currentBack] + edge.weight;
+                int newDist = distBackward[currentNodeB] + edge.weight;
 
                 if (newDist < distBackward[neighbor]) {
                     distBackward[neighbor] = newDist;
-                    prevBackward[neighbor] = currentBack;
-                    pqBackward.emplace(newDist, neighbor);
+                    prevBackward[neighbor] = currentNodeB;
+
+                    if (!processedBackward[neighbor]) {
+                        pqBackward.emplace(newDist, neighbor);
+                    }
                 }
 
-                if (distForward[neighbor] < INF) {
+                if (processedForward[neighbor]) {
                     int potentialCost = distForward[neighbor] + distBackward[neighbor];
                     if (potentialCost < bestCost) {
                         bestCost = potentialCost;
@@ -103,7 +112,7 @@ std::vector<int> Graph::shortest_path(int source, int target, int& totalTime) {
             }
         }
 
-        // Finish if the best cost is finalized
+        // Sortie anticipée si on a trouvé un chemin
         if (meetingNode != -1) break;
     }
 
@@ -114,15 +123,24 @@ std::vector<int> Graph::shortest_path(int source, int target, int& totalTime) {
 
     totalTime = bestCost;
 
-    // Reconstruct the path
+    // Reconstruction du chemin
     std::vector<int> path;
+    path.reserve(n); // Réserver la capacité maximale possible pour éviter les réallocations
+
+    // Construire le chemin avant et l'ajouter directement au chemin final
+    int forwardPathSize = 0;
     for (int node = meetingNode; node != -1; node = prevForward[node]) {
         path.push_back(node);
+        forwardPathSize++;
     }
-    std::reverse(path.begin(), path.end());
+
+    // Inverser la partie avant du chemin pour obtenir le chemin complet
+    std::reverse(path.begin(), path.begin() + forwardPathSize);
+
+    // Construire le chemin arrière et l'ajouter directement au chemin final
     for (int node = prevBackward[meetingNode]; node != -1; node = prevBackward[node]) {
         path.push_back(node);
     }
 
     return path;
-}
+}
\ No newline at end of file
diff --git a/src/preprocessing.cpp b/src/preprocessing.cpp
index 3f10b58..004a71a 100644
--- a/src/preprocessing.cpp
+++ b/src/preprocessing.cpp
@@ -4,11 +4,12 @@
 #include <stdexcept>
 #include <algorithm>
 #include <iostream>
+#include <unordered_map>
 
 #define SECRET_DELIMITER ","
 
 // Alias for connections
-using TPDF_CONNECTIONS = std::unordered_set<std::string>;
+using TPDF_CONNECTIONS = std::unordered_map<int, std::unordered_set<int>>;
 
 // Data processing to populate the graph
 void process_chunk(
@@ -36,10 +37,7 @@ void process_chunk(
             continue; // Ignore invalid connections or loops
         }
 
-        std::string connection = std::to_string(landmarkA) + SECRET_DELIMITER + std::to_string(landmarkB);
-        std::string reverseConnection = std::to_string(landmarkB) + SECRET_DELIMITER + std::to_string(landmarkA);
-
-        if (seenConnections.count(connection) > 0 || seenConnections.count(reverseConnection) > 0) {
+        if (seenConnections[landmarkA].count(landmarkB) > 0 || seenConnections[landmarkB].count(landmarkA) > 0) {
             continue; // Ignore duplicate connections
         }
 
@@ -47,8 +45,8 @@ void process_chunk(
         graph.add_edge(landmarkA, landmarkB, time);
 
         // Mark connections as seen
-        seenConnections.insert(connection);
-        seenConnections.insert(reverseConnection);
+        seenConnections[landmarkA].insert(landmarkB);
+        seenConnections[landmarkB].insert(landmarkA);
 
         // Update maxId
         maxId.store(std::max(maxId.load(), std::max(landmarkA, landmarkB)));
@@ -69,4 +67,4 @@ bool preprocess_data(const std::string& filePath, int maxLines, Graph& graph) {
 
     inputFile.close();
     return true;
-}
+}
\ No newline at end of file
diff --git a/src/shortest_path b/src/shortest_path
index 0bd9236..796a7ad 100755
Binary files a/src/shortest_path and b/src/shortest_path differ