[20251031] BOJ / P5 / 비숍 / 김민진

zinnnn37/202510/31 BOJ P5 비숍.md

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+```java
+import java.io.*;
+import java.util.ArrayList;
+import java.util.List;
+
+public class BJ_1799_비숍 {
+
+	private static final BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+	private static final BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
+
+	private static int N, blackAns, whiteAns;
+	private static boolean[] diag1, diag2; // 각각 \, / 대각선 비교
+	private static List<Point> black, white;
+
+	private static class Point {
+		int x;
+		int y;
+
+		Point(int x, int y) {
+			this.x = x;
+			this.y = y;
+		}
+	}
+
+	public static void main(String[] args) throws IOException {
+		init();
+		sol();
+	}
+
+	private static void init() throws IOException {
+		N = Integer.parseInt(br.readLine());
+
+		diag1 = new boolean[2 * N];
+		diag2 = new boolean[2 * N];
+		black = new ArrayList<>();
+		white = new ArrayList<>();
+
+		for (int i = 0; i < N; i++) {
+			String s = br.readLine();
+			for (int j = 0; j < N; j++) {
+				char c = s.charAt(j * 2);
+
+				if (c == '1') {
+					if ((i + j) % 2 == 0) {
+						black.add(new Point(i, j));
+					} else {
+						white.add(new Point(i, j));
+					}
+				}
+			}
+		}
+	}
+
+	private static void sol() throws IOException {
+		// 검은색 칸만 탐색
+		blackAns = 0;
+		dfs(black, 0, 0);
+
+		// 흰색 칸만 탐색
+		whiteAns = 0;
+		dfs(white, 0, 0);
+
+		bw.write((blackAns + whiteAns) + "");
+		bw.flush();
+		bw.close();
+		br.close();
+	}
+
+	private static void dfs(List<Point> list, int depth, int cnt) {
+		if (list == black) {
+			blackAns = Math.max(blackAns, cnt);
+		} else {
+			whiteAns = Math.max(whiteAns, cnt);
+		}
+
+		for (int i = depth; i < list.size(); i++) {
+			Point p = list.get(i);
+			// \은 x - y가 동일함 - 음수가 될 수 있으므로 N을 더해줌
+			// /은 x + y가 동일함
+			int d1 = p.x - p.y + N;
+			int d2 = p.x + p.y;
+
+			// 해당 대각선이 이미 탐색되었으면 pass
+			if (diag1[d1] || diag2[d2]) continue;
+
+			diag1[d1] = true;
+			diag2[d2] = true;
+			dfs(list, i + 1, cnt + 1);
+			diag1[d1] = false;
+			diag2[d2] = false;
+		}
+	}
+}
+```