BOJ #17370: 육각형 우리 속의 개미

Author: ISKU

BOJ/17370/Main.java

@@ -0,0 +1,74 @@
+/*
+ * Author: Minho Kim (ISKU)
+ * Date: July 27, 2019
+ * E-mail: minho.kim093@gmail.com
+ *
+ * https://github.com/ISKU/Algorithm
+ * https://www.acmicpc.net/problem/17370
+ */
+
+import java.io.*;
+
+public class Main {
+
+	private static boolean[][] map;
+	private static int N, answer;
+
+	public static void main(String[] args) throws Exception {
+		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
+		N = Integer.parseInt(br.readLine());
+
+		map = new boolean[50][50];
+		map[25][25] = true;
+
+		dfs(24, 25, 1, 0);
+		System.out.println(answer);
+	}
+
+	private static void dfs(int y, int x, int dir, int depth) {
+		if (depth == N) {
+			if (map[y][x])
+				answer++;
+			return;
+		}
+		if (map[y][x])
+			return;
+
+		if (dir == 1) {
+			map[y][x] = true;
+			dfs(y - 1, x + 1, 3, depth + 1);
+			dfs(y - 1, x - 1, 5, depth + 1);
+			map[y][x] = false;
+		}
+		else if (dir == 2) {
+			map[y][x] = true;
+			dfs(y + 1, x + 1, 4, depth + 1);
+			dfs(y + 1, x - 1, 6, depth + 1);
+			map[y][x] = false;
+		}
+		else if (dir == 3) {
+			map[y][x] = true;
+			dfs(y - 1, x, 1, depth + 1);
+			dfs(y + 1, x + 1, 4, depth + 1);
+			map[y][x] = false;
+		}
+		else if (dir == 4) {
+			map[y][x] = true;
+			dfs(y + 1, x, 2, depth + 1);
+			dfs(y - 1, x + 1, 3, depth + 1);
+			map[y][x] = false;
+		}
+		else if (dir == 5) {
+			map[y][x] = true;
+			dfs(y - 1, x, 1, depth + 1);
+			dfs(y + 1, x - 1, 6, depth + 1);
+			map[y][x] = false;
+		}
+		else {
+			map[y][x] = true;
+			dfs(y + 1, x, 2, depth + 1);
+			dfs(y - 1, x - 1, 5, depth + 1);
+			map[y][x] = false;
+		}
+	}
+}