[20251021] BOJ / G2 / 마피아 / 김수연

suyeun84/202510/21 BOJ G2 마피아.md

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+```java
+import java.io.*;
+import java.util.*;
+
+public class boj1079 {
+    static BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+    static StringTokenizer st;
+    static void nextLine() throws Exception { st = new StringTokenizer(br.readLine()); }
+    static int nextInt() { return Integer.parseInt(st.nextToken()); }
+
+    static boolean[] isDead;
+    static int N, mafia, answer = 0;
+    static int[][] R;
+    static int[] guilty;
+    public static void main(String[] args) throws Exception {
+        nextLine();
+        N = nextInt();
+        isDead = new boolean[N];
+        guilty = new int[N];
+        mafia = -1;
+        R = new int[N][N];
+        nextLine();
+        for (int i = 0; i < N; i++) guilty[i] = nextInt();
+        for (int i = 0; i < N; i++) {
+            nextLine();
+            for (int j = 0; j < N; j++) {
+                R[i][j] = nextInt();
+            }
+        }
+        nextLine();
+        mafia = nextInt();
+        dfs(N, 0);
+
+        System.out.println(answer);
+    }
+
+    static void dfs(int alive, int nights) {
+        if (isDead[mafia] || alive == 1) {
+            answer = Math.max(answer, nights);
+            return;
+        }
+        if (alive % 2 == 0) { // 밤
+            for (int i = 0; i < N; i++) {
+                if (isDead[i] || i == mafia) continue;
+                isDead[i] = true;
+                changeGuilty(1, i);
+                dfs(alive-1, nights+1);
+                changeGuilty(-1, i);
+                isDead[i] = false;
+            }
+        } else { // 낮
+            int maxGuilty = Integer.MIN_VALUE;
+            int idx = -1;
+            for (int i = 0; i < N; i++) {
+                if (isDead[i] || guilty[i] <= maxGuilty) continue;
+                maxGuilty = guilty[i];
+                idx = i;
+            }
+            isDead[idx] = true;
+            dfs(alive-1, nights);
+            isDead[idx] = false;
+        }
+    }
+
+    static void changeGuilty(int type, int idx) {
+        for (int i = 0; i < N; i++) {
+            if (isDead[i]) continue;
+            guilty[i] += type * R[idx][i];
+        }
+    }
+ }
+```