[20250721] BAJ/G3/감시/김득호

Ho/202507/21 감시.md

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+```java
+import java.io.BufferedReader;
+import java.io.IOException;
+import java.io.InputStreamReader;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.StringTokenizer;
+
+public class Main {
+    static int N,M;
+    static int[][] grid;
+
+    static int[] drs = {1, 0, -1, 0};
+    static int[] dcs = {0, 1, 0, -1};
+    static int cnt = 0;
+    static int ans;
+
+    static List<Cctv> cctvs = new ArrayList<>();
+    static List<Integer> orders = new ArrayList<>();
+
+    static int[][] visited;
+    static int[][] cmd = {
+            {0},
+            {0, 2},
+            {0, 1},
+            {0, 1, 2},
+            {0, 1, 2, 3}
+    };
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        StringTokenizer st = new StringTokenizer(br.readLine());
+
+        N = Integer.parseInt(st.nextToken());
+        M = Integer.parseInt(st.nextToken());
+
+        grid = new int[N][M];
+
+        ans = N * M;
+
+        for (int i = 0; i < N; i++) {
+            st = new StringTokenizer(br.readLine());
+            for (int j = 0; j < M; j++) {
+                grid[i][j] = Integer.parseInt(st.nextToken());
+                if(grid[i][j] == 0) cnt++;
+                if(grid[i][j] >= 1 && grid[i][j] <= 5) {
+                    cctvs.add(new Cctv(i, j, grid[i][j] - 1));
+                }
+            }
+        }
+
+        simulate();
+        System.out.println(ans);
+    }
+
+    private static void simulate() {
+        dfs(0,0);
+    }
+
+    private static void dfs(int idx,int depth) {
+        if(depth == cctvs.size()) {
+            calcCctvRange();
+            return;
+        }
+
+        for (int i = 0; i < 4; i++) {
+            if(ans == 0) return;
+            orders.add(i);
+            dfs(idx, depth + 1);
+            orders.remove(orders.size() - 1);
+        }
+    }
+
+    private static void calcCctvRange() {
+        int temp = cnt;
+        visited = new int[N][M];
+        for (int i = 0; i < orders.size(); i++) {
+            Cctv current = cctvs.get(i);
+
+            for (int j = 0; j < cmd[current.type].length; j++) {
+                // 가시구역
+                mark(current.r, current.c, current.type, orders.get(i), j);
+            }
+        }
+
+        ans = Math.min(cnt, ans);
+        cnt = temp;
+    }
+
+    private static void mark(int r, int c, int idx,int cmdIdx,int dir) {
+        int nr = r + drs[(cmd[idx][dir] + cmdIdx) % 4];
+        int nc = c + dcs[(cmd[idx][dir] + cmdIdx) % 4];
+
+        while(canSee(nr,nc)) {
+            if(visited[nr][nc] == 0 && !isCctv(nr,nc)) {
+                visited[nr][nc]++;
+                cnt--;
+            }
+
+            nr = nr + drs[(cmd[idx][dir] + cmdIdx) % 4];
+            nc = nc + dcs[(cmd[idx][dir] + cmdIdx) % 4];
+        }
+    }
+
+    private static boolean isCctv(int r, int c) {
+        return grid[r][c] >= 1 && grid[r][c] <= 5;
+    }
+
+    private static boolean canSee(int r, int c) {
+        if(!inRange(r,c)) return false;
+        if(grid[r][c] == 6) return false;
+        return true;
+    }
+
+    private static boolean inRange(int r, int c) {
+        return r >= 0 && r < N && c >= 0 && c < M;
+    }
+
+    static class Cctv {
+        int r, c, type;
+
+        public Cctv(int r, int c, int type) {
+            this.r = r;
+            this.c = c;
+            this.type = type;
+        }
+    }
+}
+```