29-g0rnn

g0rnn/README.md

@@ -30,4 +30,5 @@
 | 26차시 | 2025.05.26 | 구현 | [서버 증설 횟수](https://school.programmers.co.kr/learn/courses/30/lessons/389479?language=java) | https://github.com/AlgoLeadMe/AlgoLeadMe-12/pull/106 |
 | 27차시 | 2025.06.15 | Floyd-Warshall | [케빈 베이컨의 6단계 법칙](https://www.acmicpc.net/problem/1389) | https://github.com/AlgoLeadMe/AlgoLeadMe-12/pull/113 |
 | 28차시 | 2025.06.27 | BFS | [상어 중학교](https://www.acmicpc.net/problem/21609) | https://github.com/AlgoLeadMe/AlgoLeadMe-12/pull/115 |
+| 29차시 | 2025.07.22 | combination | [소문난 칠공주](https://www.acmicpc.net/problem/1941) | https://github.com/AlgoLeadMe/AlgoLeadMe-12/pull/119 |
 ---

g0rnn/combination/29-g0rnn.java

@@ -0,0 +1,72 @@
+package beakjoon;
+
+import java.util.*;
+import java.io.*;
+
+public class Sol1941 {
+
+    static int ans = 0;
+    static char[][] board = new char[5][5];
+    static int[][] offset = {{1, 0}, {0, 1}, {-1, 0}, {0, -1}};
+    static List<Integer> selected = new ArrayList<>();
+
+    public static void main(String[] args) throws IOException {
+        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+        for (int i = 0; i < 5; i++) {
+            board[i] = br.readLine().toCharArray(); 
+        }
+        br.close();
+
+        comb(0, 0);
+        System.out.println(ans);
+    }
+
+    // 조합을 만들고 뽑은 칸이 연속적이면서 & S가 4개 이상인지 확인
+    private static void comb(int start, int depth) {
+        if (depth == 7) {
+            if (isValid()) {
+                ans++;
+            }
+            return;
+        }
+
+        for (int i = start; i < 25; i++) {
+            selected.add(i);
+            comb(i + 1, depth + 1);
+            selected.remove(selected.size() - 1);
+        }
+    }
+
+    private static boolean isValid() {
+        int cntS = 0;
+        boolean[] check = new boolean[25];
+        Queue<Integer> q = new ArrayDeque<>();
+        q.offer(selected.get(0));
+        check[selected.get(0)] = true;
+
+        int countVisited = 1; // 방문한 칸의 수
+        if (board[selected.get(0) / 5][selected.get(0) % 5] == 'S') cntS++;
+
+        while (!q.isEmpty()) {
+            int now = q.poll();
+            int x = now % 5;
+            int y = now / 5;
+
+            for (int[] o : offset) {
+                int nx = x + o[0];
+                int ny = y + o[1];
+                int next = ny * 5 + nx;
+
+                if (nx < 0 || nx >= 5 || ny < 0 || ny >= 5) continue;
+                if (!selected.contains(next)) continue; // 내가 선택한 칸만 이동하도록
+                if (check[next]) continue;
+
+                check[next] = true;
+                q.offer(next);
+                countVisited++;
+                if (board[ny][nx] == 'S') cntS++;
+            }
+        }
+        return countVisited == 7 && cntS >= 4;
+    }
+}