Refactor move function to return success status

node.c

@@ -13,7 +13,11 @@ Node *generate_child_node(const Node *parent, const Direction direction) {
 
     *new_state = *(parent->state);
 
-    move(new_state, direction);
+    // Free new_state if move fails
+    if (!move(new_state, direction)) {
+        free(new_state);
+        return NULL;
+    }
 
     Node *child = (Node *)malloc(sizeof(Node));
     if (!child) {
@@ -24,7 +28,7 @@ Node *generate_child_node(const Node *parent, const Direction direction) {
     child->parent = (Node *)parent;
     child->state = new_state;
     child->move = direction;
-    child->cost = 0;
+    child->cost = parent->cost + 1;
 
     return child;
 }

puzzle.c

@@ -85,7 +85,7 @@ int is_valid_move(const Puzzle *p, const Direction direction) {
     }
 }
 
-void move(Puzzle *p, const Direction direction) {
+int move(Puzzle *p, const Direction direction) {
     int blank_row = p->blank_index / PUZZLE_SIZE;
     int blank_col = p->blank_index % PUZZLE_SIZE;
 
@@ -106,16 +106,18 @@ void move(Puzzle *p, const Direction direction) {
             new_col++;
             break;
         case NONE:
-            return;
+            return 0;  // No move made
     }
 
     if (new_row < 0 || new_row >= PUZZLE_SIZE || new_col < 0 || new_col >= PUZZLE_SIZE) {
-        return;
+        return 0;  // Move is out of bounds
     }
 
     int new_index = new_row * PUZZLE_SIZE + new_col;
     swap(&p->board[p->blank_index], &p->board[new_index]);
     p->blank_index = new_index;
+
+    return 1;  // Move successful
 }
 
 void print_puzzle(const Puzzle *p, int debug) {

puzzle.h

@@ -19,7 +19,7 @@ int get_blank_index(const Puzzle *p);
 int get_inversion_count(const Puzzle puzzle);
 int is_solvable(const Puzzle puzzle);
 int is_valid_move(const Puzzle *p, const Direction direction);
-void move(Puzzle *p, const Direction direction);
+int move(Puzzle *p, const Direction direction);
 void print_puzzle(const Puzzle *p, int debug);
 void shuffle(Puzzle *p);
 void swap(int *a, int *b);