Merge pull request #627 from AlgorithmWithGod/JHLEE325

[20250808] BOJ / G4 /뱀 / 이준희

Author: ShinHeeEul

JHLEE325/202508/08 BOJ G4 뱀.md

@@ -0,0 +1,80 @@
+```java
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    static int n, k, l;
+    static int[][] board;
+    static Deque<int[]> snake = new ArrayDeque<>();
+    static Map<Integer, Character> dirMap = new HashMap<>();
+
+    static int[][] dir = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
+
+    public static void main(String[] args) throws Exception {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st;
+
+        n = Integer.parseInt(br.readLine());
+        k = Integer.parseInt(br.readLine());
+        board = new int[n][n];
+
+        for (int i = 0; i < k; i++) {
+            st = new StringTokenizer(br.readLine());
+            int r = Integer.parseInt(st.nextToken()) - 1;
+            int c = Integer.parseInt(st.nextToken()) - 1;
+            board[r][c] = 2;
+        }
+
+        l = Integer.parseInt(br.readLine());
+        for (int i = 0; i < l; i++) {
+            st = new StringTokenizer(br.readLine());
+            int t = Integer.parseInt(st.nextToken());
+            char d = st.nextToken().charAt(0);
+            dirMap.put(t, d);
+        }
+
+        System.out.println(simulate());
+    }
+
+    static int simulate() {
+        int time = 0;
+        int direction = 0;
+        int x = 0, y = 0;
+
+        snake.offerLast(new int[]{y, x});
+        board[y][x] = 1;
+
+        while (true) {
+            time++;
+            int dy = y + dir[direction][0];
+            int dx = x + dir[direction][1];
+
+            if (!(0 <= dy && dy < n && 0 <= dx && dx < n) || board[dy][dx] == 1) break;
+
+            if (board[dy][dx] == 2) {
+                board[dy][dx] = 1;
+                snake.offerLast(new int[]{dy, dx});
+            } else {
+                board[dy][dx] = 1;
+                snake.offerLast(new int[]{dy, dx});
+                int[] tail = snake.pollFirst();
+                board[tail[0]][tail[1]] = 0;
+            }
+
+            if (dirMap.containsKey(time)) {
+                char turn = dirMap.get(time);
+                if (turn == 'L') direction = (direction + 3) % 4;
+                else if (turn == 'D') direction = (direction + 1) % 4;
+            }
+
+            y = dy;
+            x = dx;
+        }
+
+        return time;
+    }
+
+}
+
+```