Plugging the memory lead

du4/a_train.c

@@ -42,24 +42,43 @@ void cancel_train(struct car* first) {
 
 
 struct car* clear_train(struct car* first, const char* target) {
-  struct car* curr = first;
-    struct car* prev = NULL;
-
-    while (curr) {
-        if (strcmp(curr->value, target) == 0) {
-            struct car* to_delete = curr;
-            if (prev)
-                prev->next = curr->next;
-            else
-                first = curr->next;
-            curr = curr->next;
-            free(to_delete);
-        } else {
-            prev = curr;
-            curr = curr->next;
-        }
+ if(first == NULL){
+        return NULL;
     }
+    if (first->next == NULL && strcmp(first->value, target) == 0)
+    {
+        free(first);
+        return NULL;
+    }
+    else if(first->next == NULL && strcmp(first->value, target) != 0){
+        return first;
+    }
+    if(first->next->next == NULL && strcmp(first->value, target) == 0){
+       struct car* temp = first;
+       first = first->next;
+       first->next = NULL;
+       free(temp);
+       return first;
 
-    return first;
+    }
+    struct car* prev= NULL;
+    struct car* temp = first;
+    while (temp->next)
+    { 
+        if(strcmp(temp->value, target) == 0){
+         struct car* targetNode = temp;
+        prev->next = temp->next;
+        temp = temp->next;
+        free(targetNode);
+
+    }
+    else{
+        prev = temp;
+        temp = temp->next;
+    }
+    
+    }
+    
+	return first;
 }