small improvement & fixes.

- fix the max number of landmark selected.
- rework the selection of landmark in ALT preprocessing to start by the smallest node ID.
- fix getOneOrTwo issue who take all integrer number in entry.
- fix API only to take poitive integrer and return error if not the exact type. (for example : 1ABC will prune to 1, but now, it will just return an error "INVALID PARAMETER").
- return an error when the graph is empty at preprocessing time.

Author: qwert1871

src/alt.cpp

@@ -18,7 +18,7 @@
  * Steps of the Algorithm:
  * 1. If `save_alt` is enabled, attempt to load precomputed landmark data from storage.
  * 2. Initialize storage structures for distance calculations.
- * 3. Select the first landmark as an arbitrary node (first node in the dataset).
+ * 3. Select the first landmark as the node with the smallest ID (e.g., ID 1 if available).
  * 4. Compute shortest-path distances using Dijkstra’s algorithm:
  *    - `dist_landmark[i][j]` stores the shortest path distance from landmark `j` to node `i`.
  * 5. Iteratively select `nb_alt` landmarks using the farthest-node heuristic:
@@ -72,7 +72,13 @@ void preprocessAlt(graph& gdata, config& conf)
 
     gdata.dist_landmark.resize(n, std::vector<int>(conf.nb_alt, -1));
 
-    int fl = gdata.node_to_index.begin()->first;
+    int fl = std::numeric_limits<int>::max();
+    for (const auto& kv : gdata.node_to_index)
+    {
+        if (kv.first < fl)
+            fl = kv.first;
+    }
+    
     landmarks.push_back(fl);
     console("info", "processing landmark " + std::to_string(fl) + " (1/" + std::to_string(conf.nb_alt) + ")");
     logger("processing landmark " + std::to_string(fl) + " (1/" + std::to_string(conf.nb_alt) + ")");
@@ -87,6 +93,8 @@ void preprocessAlt(graph& gdata, config& conf)
                 md[idx] = d[idx];
         }
     }
+    
+    md[gdata.node_to_index[fl]] = -1;
 
     for (int i = 1; i < conf.nb_alt; ++i) {
         int nl = -1;

src/api.cpp

@@ -224,7 +224,12 @@ int launchApiGateway(const graph& gdata, search_buffers& buffers, const config&
                     try {
                         size_t amp_pos = query_part.find("&", st_pos);
                         std::string val = query_part.substr(st_pos + 6, amp_pos - (st_pos + 6));
-                        start_val = std::stoi(val);
+                        size_t consumed = 0;
+                        int parsed = std::stoi(val, &consumed);
+                        if (consumed != val.size()) {
+                            throw std::invalid_argument("invalid integer parameter");
+                        }
+                        start_val = parsed;
                         start_ok = true;
                     }
                     catch (...) {
@@ -238,7 +243,12 @@ int launchApiGateway(const graph& gdata, search_buffers& buffers, const config&
                     try {
                         size_t amp_pos = query_part.find("&", en_pos);
                         std::string val = query_part.substr(en_pos + 4, amp_pos - (en_pos + 4));
-                        end_val = std::stoi(val);
+                        size_t consumed = 0;
+                        int parsed = std::stoi(val, &consumed);
+                        if (consumed != val.size()) {
+                            throw std::invalid_argument("invalid integer parameter");
+                        }
+                        end_val = parsed;
                         end_ok = true;
                     }
                     catch (...) {

src/csv.cpp

@@ -176,6 +176,12 @@ bool readCSV(const std::string& map_path, std::vector<edge>& edges)
     logger("total lines read: " + std::to_string(line_num));
     logger("total valid edges loaded: " + std::to_string(valid_lines));
 
+    if (edges.size() == 0) {
+        logger("error: no valid edges loaded. graph is empty.");
+        console("error", "no valid edges loaded. graph is empty.");
+        return false;
+    }
+
     return true;
 }
 

src/decl.h

@@ -177,7 +177,7 @@ void clear();
 int getInteger(const std::string& prompt);
 double getPercentage(const std::string& prompt);
 bool getYesNo(const std::string& prompt);
-double getOneOrTwo(const std::string& prompt);
+int getOneOrTwo(const std::string& prompt);
 
 void initializeSearchBuffers(const graph& gdata, search_buffers& buffers);
 

src/helper.cpp

@@ -163,12 +163,12 @@ double getPercentage(const std::string& prompt)
  * @param prompt The message displayed to the user.
  * @return '1' or '2'.
  */
-double getOneOrTwo(const std::string& prompt)
+int getOneOrTwo(const std::string& prompt)
 {
     int one_or_two;
     while (true) {
         one_or_two = getInteger(prompt);
-        if (one_or_two != 1 || one_or_two != 2) {
+        if (one_or_two == 1 || one_or_two == 2) {
             break;
         }
         console("error", "invalid input. please enter 1 or 2.");