1

du4/a_train.c

@@ -1,18 +1,85 @@
-#include "a_train.h"
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include "a_train.h"
 
-struct car* add_car(struct car* first,const char* target) {
+/**
-    return NULL;
+ * Prida vozen na koniec vlaku.
+ */
+struct car* add_car(struct car* first, const char* target) {
+    // vytvorenie noveho vozna
+    struct car* newcar = calloc(1, sizeof(struct car));
+    if (newcar == NULL) {
+        return first; // ak zlyha alokacia, vrat povodny zoznam
+    }
+
+    strcpy(newcar->value, target);
+    newcar->next = NULL;
+
+    // ak je vlak prazdny
+    if (first == NULL) {
+        return newcar;
+    }
+
+    // najdi posledny vozen
+    struct car* this = first;
+    while (this->next != NULL) {
+        this = this->next;
+    }
+
+    // pripoj novy vozen
+    this->next = newcar;
+    return first;
 }
-dddddddd
+
+/**
+ * Vypise vsetky vozne vo vlaku.
+ */
 void print_train(struct car* first) {
+    struct car* this = first;
+    while (this != NULL) {
+        printf("%s\n", this->value);
+        this = this->next;
+    }
 }
 
+/**
+ * Zrusenie vsetkych voznov vo vlaku.
+ */
 void cancel_train(struct car* first) {
+    if (first == NULL) return;
+
+    // rekurzivne uvolnenie
+    cancel_train(first->next);
+    free(first);
 }
 
-
+/**
+ * Vyradenie vsetkych voznov, ktorych cielova stanica je target.
+ */
 struct car* clear_train(struct car* first, const char* target) {
-	return NULL;
+    struct car* current = first;
-}
+    struct car* prev = NULL;
 
+    while (current != NULL) {
+        if (strcmp(current->value, target) == 0) {
+            // treba zmazat tento vozen
+            struct car* to_delete = current;
+            if (prev == NULL) {
+                // mazeme prvy prvok
+                first = current->next;
+            } else {
+                // mazeme stredny alebo posledny prvok
+                prev->next = current->next;
+            }
+            current = current->next;
+            free(to_delete);
+        } else {
+            // presun dalej
+            prev = current;
+            current = current->next;
+        }
+    }
+
+    return first;
+}