Update 'cv4/a_train.c'

cv4/a_train.c

@@ -0,0 +1,67 @@
+#include "train.h"
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct car* add_car(struct car* first, const char* target) {
+    struct car* new_car = (struct car*)calloc(1, sizeof(struct car));
+    if (new_car == NULL) {
+        return first;
+    }
+    
+    strcpy(new_car->value, target);
+    new_car->next = NULL;
+    
+    if (first == NULL) {
+        return new_car;  
+    } else {
+        struct car* current = first;
+        while (current->next != NULL) {
+            current = current->next;
+        }
+        current->next = new_car;  
+        return first;
+    }
+}
+
+void print_train(struct car* first) {
+    struct car* current = first;
+        while (current != NULL) {
+            printf("%s\n", current->value);
+            current = current->next;
+        }
+}
+
+void cancel_train(struct car* first) {
+    while (first != NULL) {
+        struct car* current = first;
+        first = first->next;
+        free(current);
+    }
+}
+
+struct car* clear_train(struct car* first, const char* target) {
+    struct car* new_first = first;
+    struct car* prev = NULL;
+    struct car* current = first;
+
+    while (current != NULL) {
+        if (strcmp(current->value, target) == 0) {
+            if (prev == NULL) {
+                new_first = current->next;
+                free(current);
+                current = new_first;
+            } else {
+                prev->next = current->next;
+                free(current);
+                current = prev->next;
+            }
+        
+        } else {
+            prev = current;
+            current = current->next;
+        }
+    }
+    
+    return new_first;
+}