Fixing segfault

du5/a_station.c

@@ -28,56 +28,34 @@ int select_track(struct station* station, const char* target){
 }
 
 void add_target_capacity(struct station* station,const char* target, int capacity){
-    struct car* ptr = *station->tracks;
-   int count = 0;
-   int res = select_track(station, target);
-   while(ptr){
-    if(count == res){
-        break;
-    }
-   if (strcmp(ptr->value, target) ==0 ){
-        ptr->capacity += capacity;
+       int res = select_track(station, target);
+    struct car* previous = NULL;
+    struct car** ptr = &station->tracks[res];
+    struct car* head = *ptr;
+
+   while(head){
+    if(strcmp(head->value, target) == 0){
+        head->capacity += capacity;
         return;
     }
+    previous = head;
 
-    ptr = ptr->next;
-    count++;
+    head = head->next;
+    
 
    }
-   if(count < res){
-    struct car* next = (struct car*)calloc(1, sizeof(struct car));
-    strcpy(next->value, target);
-    next->capacity = capacity;
-    if(ptr){
-    ptr->next = next;
-    return;}
-    else{
-        *station->tracks = next;
-        return;
-    }
+   struct car* next = (struct car*)calloc(1, sizeof(struct car));
+   strcpy(next->value, target);
+   next->capacity = capacity;
+   if(previous){
+    previous->next = next;
    }
-   else if (count == res && ptr && strcmp(ptr->value, target) != 0){
-    struct car* next = (struct car*)calloc(1, sizeof(struct car));
-    strcpy(next->value, target);
-    next->capacity = capacity;
-    if(ptr){
-    ptr->next = next;
-     return;}
-     else{
-        *station->tracks = next;
-        return;
-    }
-
-
+   else{
+    *ptr = next;
    }
-   if (!ptr){
-    return;
-   }
-   ptr->capacity += capacity;
-   return;
+}
    
 
-}
 
 int get_target_capacity(struct station* station,const char* target){
     struct car* ptr = *station->tracks;
@@ -109,9 +87,13 @@ int count_targets(struct station* station){
 }
 
 int count_capacity(struct station* station){
-    int total = 0;
-for (struct car* ptr = *station->tracks; ptr; ptr = ptr->next)
-    total += ptr->capacity;
-return total;
+    int res  = 0;
+    struct car* ptr = *station->tracks;
+    while (ptr){
+        res += ptr->capacity;
+        ptr = ptr->next;
+
+    }
+    return res;
 }