From 3d702f81b2872360ef62aeca92afa459e6ea5fab Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Daniel=20Dembick=C3=BD?= <daniel.dembicky@student.tuke.sk>
Date: Fri, 17 Apr 2026 06:53:30 +0000
Subject: [PATCH] =?UTF-8?q?P=C5=99idat=20du4/program.c?=
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---
 du4/program.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 du4/program.c

diff --git a/du4/program.c b/du4/program.c
new file mode 100644
index 0000000..25e5eab
--- /dev/null
+++ b/du4/program.c
@@ -0,0 +1,66 @@
+#include "snake.h"
+#include <stdlib.h>
+ 
+struct snake* add_snake(struct snake* snake, int x, int y){
+    struct snake* head = malloc(sizeof(struct snake));
+    head->x = x;
+    head->y = y;
+    head->next = snake;
+    return head;
+}
+ 
+struct snake* remove_snake(struct snake* snake){
+    if(snake == NULL) return NULL;
+    if(snake->next == NULL){
+        free(snake);
+        return NULL;
+    }
+    struct snake* cur = snake;
+    while(cur->next->next != NULL)
+        cur = cur->next;
+    free(cur->next);
+    cur->next = NULL;
+    return snake;
+}
+ 
+void free_snake(struct snake* sn){
+    while(sn != NULL){
+        struct snake* tmp = sn->next;
+        free(sn);
+        sn = tmp;
+    }
+}
+ 
+int is_snake(struct snake* snake, int x, int y){
+    while(snake != NULL){
+        if(snake->x == x && snake->y == y) return 1;
+        snake = snake->next;
+    }
+    return 0;
+}
+ 
+int step_state(struct state* st){
+    int nx = st->snake->x + st->sx;
+    int ny = st->snake->y + st->sy;
+ 
+    if(nx < 0 || nx >= st->width || ny < 0 || ny >= st->height)
+        return END_WALL;
+ 
+    if(is_snake(st->snake, nx, ny))
+        return END_SNAKE;
+ 
+    for(int i = 0; i < FOOD_COUNT; i++){
+        if(st->foodx[i] == nx && st->foody[i] == ny){
+            st->snake = add_snake(st->snake, nx, ny);
+            st->foodx[i] = -1;
+            st->foody[i] = -1;
+            for(int j = 0; j < FOOD_COUNT; j++)
+                if(st->foodx[j] >= 0) return END_CONTINUE;
+            return END_FOOD;
+        }
+    }
+ 
+    st->snake = add_snake(st->snake, nx, ny);
+    st->snake = remove_snake(st->snake);
+    return END_CONTINUE;
+}
\ No newline at end of file