[20251231] BOJ / G3 / 레이저 통신 / 김민진

zinnnn37/202512/31 BOJ G3 레이저 통신.md

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+```java
+import java.awt.*;
+import java.io.*;
+import java.util.*;
+import java.util.Queue;
+
+public class BJ_6087_레이저_통신 {
+
+    private static final int[] dx = { -1, 1, 0, 0 };
+    private static final int[] dy = { 0, 0, -1, 1 };
+
+    private static final BufferedReader  br = new BufferedReader(new InputStreamReader(System.in));
+    private static final BufferedWriter  bw = new BufferedWriter(new OutputStreamWriter(System.out));
+    private static       StringTokenizer st;
+
+    private static int W, H, ans;
+    private static Point start, end;
+    private static char[][]    matrix;
+    private static int[][][]   visited;
+    private static Queue<Node> pq;
+
+    private static class Node implements Comparable<Node> {
+        int x;
+        int y;
+        int dir;
+        int cnt;
+
+        public Node(int x, int y, int dir, int cnt) {
+            this.x = x;
+            this.y = y;
+            this.dir = dir;
+            this.cnt = cnt;
+        }
+
+        @Override
+        public int compareTo(Node o) {
+            return Integer.compare(this.cnt, o.cnt);
+        }
+
+    }
+
+    public static void main(String[] args) throws IOException {
+        init();
+        sol();
+    }
+
+    private static void init() throws IOException {
+        st = new StringTokenizer(br.readLine());
+        W = Integer.parseInt(st.nextToken());
+        H = Integer.parseInt(st.nextToken());
+
+        visited = new int[H][W][4];
+        for (int i = 0; i < H; i++) {
+            for (int j = 0; j < W; j++) {
+                Arrays.fill(visited[i][j], Integer.MAX_VALUE);
+            }
+        }
+
+        pq = new PriorityQueue<>();
+        matrix = new char[H][W];
+        for (int i = 0; i < H; i++) {
+            String line = br.readLine();
+            for (int j = 0; j < W; j++) {
+                matrix[i][j] = line.charAt(j);
+
+                if (matrix[i][j] == 'C') {
+                    if (Objects.isNull(start)) {
+                        start = new Point(i, j);
+                        for (int d = 0; d < 4; d++) {
+                            visited[i][j][d] = 0;
+                            pq.offer(new Node(i, j, d, 0));
+                        }
+                    } else {
+                        end = new Point(i, j);
+                    }
+                }
+            }
+        }
+    }
+
+    private static void sol() throws IOException {
+        while (!pq.isEmpty()) {
+            Node cur = pq.poll();
+
+            if (cur.x == end.x && cur.y == end.y) {
+                int ans = Integer.MAX_VALUE;
+                for (int d = 0; d < 4; d++) {
+                    ans = Math.min(ans, visited[end.x][end.y][d]);
+                }
+                bw.write(ans + "");
+                break;
+            }
+
+            if (cur.cnt > visited[cur.x][cur.y][cur.dir]) continue;
+
+            for (int d = 0; d < 4; d++) {
+                if (d == (cur.dir ^ 1)) continue;
+
+                int nx = cur.x + dx[d];
+                int ny = cur.y + dy[d];
+
+                if (OOB(nx, ny) || matrix[nx][ny] == '*') continue;
+
+                int nCnt = cur.cnt + (d == cur.dir ? 0 : 1);
+
+                if (visited[nx][ny][d] > nCnt) {
+                    visited[nx][ny][d] = nCnt;
+                    pq.offer(new Node(nx, ny, d, nCnt));
+                }
+            }
+        }
+        bw.flush();
+        bw.close();
+        br.close();
+    }
+
+    private static boolean OOB(int x, int y) {
+        return x < 0 || H <= x || y < 0 || W <= y;
+    }
+
+}
+```