[BruteForce] baekjoon-17471

Author: Seogeurim

README.md

@@ -84,6 +84,7 @@
 | 09  | ⭐️ | [SWEA-3234 준환이의 양팔저울](./src/BruteForce/swea3234)    |      |
 | 10  | ⭐️ | [Baekjoon-17136 색종이 붙이기](./src/BruteForce/P17136)    | 삼성 A형 기출 |
 | 11  |     | [Baekjoon-2468 안전 영역](./src/BruteForce/P2468)        |      |
+| 12  |     | [Baekjoon-17471 게리맨더링](./src/BruteForce/P17471)     | 삼성 A형 기출 |
 
 ## DFS & BFS
 

src/BruteForce/P17471/Main.java

@@ -0,0 +1,89 @@
+package BruteForce.P17471;
+
+import java.io.*;
+import java.util.*;
+
+public class Main {
+
+    static int N, ans = -1;
+    static int[] nums;
+    static ArrayList<Integer>[] graph;
+    static boolean[] selected;
+
+    public static void main(String[] args) throws Exception {
+        System.setIn(new FileInputStream("src/BruteForce/P17471/input.txt"));
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+
+        N = Integer.parseInt(br.readLine());
+        nums = new int[N+1];
+        graph = new ArrayList[N+1];
+
+        StringTokenizer st = new StringTokenizer(br.readLine());
+        for (int i = 1; i <= N; i++) nums[i] = Integer.parseInt(st.nextToken());
+
+        for (int i = 1; i <= N; i++) {
+            graph[i] = new ArrayList<>();
+            st = new StringTokenizer(br.readLine());
+            int m = Integer.parseInt(st.nextToken());
+            while (m-- > 0) graph[i].add(Integer.parseInt(st.nextToken()));
+        }
+
+        selected = new boolean[N+1];
+        for (int i = 1; i <= N/2; i++) {
+            dfs(1, 0, i);
+        }
+
+        System.out.println(ans);
+    }
+
+    static void dfs(int start, int cnt, int n) {
+        if (cnt == n) {
+            int[] A = new int[n], B = new int[N-n];
+            int a_cnt = 0, b_cnt = 0;
+            for (int i = 1, j = 0, k = 0; i <= N; i++) {
+                if (selected[i]) { A[j++] = i; a_cnt += nums[i]; }
+                else { B[k++] = i; b_cnt += nums[i]; }
+            }
+            if (check(A) && check(B)) {
+                int res = Math.abs(a_cnt - b_cnt);
+                if (ans == -1) ans = res;
+                else ans = Math.min(ans, res);
+            }
+            return;
+        }
+
+        for (int i = start; i <= N; i++) {
+            selected[i] = true;
+            dfs(i+1, cnt+1, n);
+            selected[i] = false;
+        }
+    }
+
+    static boolean check(int[] arr) {
+        Queue<Integer> q = new LinkedList<>();
+        boolean[] visited = new boolean[N+1];
+        q.offer(arr[0]);
+        visited[arr[0]] = true;
+
+        while (!q.isEmpty()) {
+            int p = q.poll();
+            for (int next : graph[p]) {
+                boolean check = false;
+                for (int a : arr) {
+                    if (next == a) {
+                        check = true;
+                        break;
+                    }
+                }
+                if (check && !visited[next]) {
+                    visited[next] = true;
+                    q.offer(next);
+                }
+            }
+        }
+        for (int a : arr) {
+            if (!visited[a]) return false;
+        }
+        return true;
+    }
+}

src/BruteForce/P17471/README.md

@@ -0,0 +1,6 @@
+## [baekjoon-17471] 게리맨더링
+
+![image](https://user-images.githubusercontent.com/22045163/112151635-ce225580-8c24-11eb-993b-c44a3ff4534d.png)
+![image](https://user-images.githubusercontent.com/22045163/112151680-d8dcea80-8c24-11eb-94aa-113efdb5fc84.png)
+
+![image](https://user-images.githubusercontent.com/22045163/112151740-e72b0680-8c24-11eb-8e6c-7b4bf2606363.png)

src/BruteForce/P17471/input.txt

@@ -0,0 +1,19 @@
+6
+2 2 2 2 2 2
+1 3
+1 4
+1 1
+1 2
+1 6
+1 5
+//-1
+
+
+6
+5 2 3 4 1 2
+2 2 4
+4 1 3 6 5
+2 4 2
+2 1 3
+1 2
+1 2