[20250904] BOJ / G1 / 2048 (Easy) / 김민진

zinnnn37/202509/4 BOJ G1 2048 (Easy).md

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+```java
+import java.io.*;
+import java.util.Arrays;
+import java.util.StringTokenizer;
+
+public class BJ_12100_2048_Easy {
+
+	private static final int UP    = 0;
+	private static final int DOWN  = 1;
+	private static final int LEFT  = 2;
+	private static final int RIGHT = 3;
+
+	private static final BufferedReader  br = new BufferedReader(new InputStreamReader(System.in));
+	private static final BufferedWriter  bw = new BufferedWriter(new OutputStreamWriter(System.out));
+	private static       StringTokenizer st;
+
+	private static int         N;
+	private static int         ans;
+	private static int[]       order;
+	private static int[][]     map;
+	private static int[][]     copiedMap;
+	private static boolean[][] visited;
+
+	public static void main(String[] args) throws IOException {
+		init();
+		sol();
+	}
+
+	private static void init() throws IOException {
+		N   = Integer.parseInt(br.readLine());
+		ans = 0;
+
+		order = new int[5];
+
+		map       = new int[N][N];
+		copiedMap = new int[N][N];
+		visited   = new boolean[N][N];
+		for (int i = 0; i < N; i++) {
+			st = new StringTokenizer(br.readLine());
+			for (int j = 0; j < N; j++) {
+				map[i][j] = Integer.parseInt(st.nextToken());
+			}
+		}
+	}
+
+	private static void sol() throws IOException {
+		dfs(0);
+
+		bw.write(ans + "");
+		bw.flush();
+		bw.close();
+		br.close();
+	}
+
+	private static void dfs(int depth) {
+		if (depth == 5) {
+			copyMap();
+			playGame();
+			updateMaxValue();
+			return;
+		}
+
+		for (int i = 0; i < 4; i++) {
+			order[depth] = i;
+			dfs(depth + 1);
+		}
+	}
+
+	private static void copyMap() {
+		for (int i = 0; i < N; i++) {
+			System.arraycopy(map[i], 0, copiedMap[i], 0, N);
+		}
+	}
+
+	private static void playGame() {
+		for (int d : order) {
+			clearVisited();
+			if (d == UP) {
+				up();
+			} else if (d == DOWN) {
+				down();
+			} else if (d == LEFT) {
+				left();
+			} else if (d == RIGHT) {
+				right();
+			}
+		}
+	}
+
+	private static void up() {
+		for (int j = 0; j < N; j++) {
+			for (int i = 1; i < N; i++) {
+				if (copiedMap[i][j] == 0) continue;
+
+				int value = copiedMap[i][j];
+				copiedMap[i][j] = 0;
+
+				int k = i - 1;
+				// 0이 아닌 블록이나 경계를 찾기
+				while (k >= 0 && copiedMap[k][j] == 0) {
+					k--;
+				}
+
+				if (k >= 0 && copiedMap[k][j] == value && !visited[k][j]) {
+					// 합치기 가능
+					copiedMap[k][j] = value * 2;
+					visited[k][j]   = true;
+				} else {
+					// 합치기 불가능 - 빈 공간에 배치
+					copiedMap[k + 1][j] = value;
+				}
+			}
+		}
+	}
+
+	private static void down() {
+		for (int j = 0; j < N; j++) {
+			for (int i = N - 2; i >= 0; i--) {
+				if (copiedMap[i][j] == 0) continue;
+
+				int value = copiedMap[i][j];
+				copiedMap[i][j] = 0;
+
+				int k = i + 1;
+				while (k < N && copiedMap[k][j] == 0) {
+					k++;
+				}
+
+				if (k < N && copiedMap[k][j] == value && !visited[k][j]) {
+					copiedMap[k][j] = value * 2;
+					visited[k][j]   = true;
+				} else {
+					copiedMap[k - 1][j] = value;
+				}
+			}
+		}
+	}
+
+	private static void left() {
+		for (int i = 0; i < N; i++) {
+			for (int j = 1; j < N; j++) {
+				if (copiedMap[i][j] == 0) continue;
+
+				int value = copiedMap[i][j];
+				copiedMap[i][j] = 0;
+
+				int k = j - 1;
+				while (k >= 0 && copiedMap[i][k] == 0) {
+					k--;
+				}
+
+				if (k >= 0 && copiedMap[i][k] == value && !visited[i][k]) {
+					copiedMap[i][k] = value * 2;
+					visited[i][k]   = true;
+				} else {
+					copiedMap[i][k + 1] = value;
+				}
+			}
+		}
+	}
+
+	private static void right() {
+		for (int i = 0; i < N; i++) {
+			for (int j = N - 2; j >= 0; j--) {
+				if (copiedMap[i][j] == 0) continue;
+
+				int value = copiedMap[i][j];
+				copiedMap[i][j] = 0;
+
+				int k = j + 1;
+				while (k < N && copiedMap[i][k] == 0) {
+					k++;
+				}
+
+				if (k < N && copiedMap[i][k] == value && !visited[i][k]) {
+					copiedMap[i][k] = value * 2;
+					visited[i][k]   = true;
+				} else {
+					copiedMap[i][k - 1] = value;
+				}
+			}
+		}
+	}
+
+	private static void updateMaxValue() {
+		for (int i = 0; i < N; i++) {
+			for (int j = 0; j < N; j++) {
+				ans = Math.max(ans, copiedMap[i][j]);
+			}
+		}
+	}
+
+	private static void clearVisited() {
+		for (int i = 0; i < N; i++) {
+			Arrays.fill(visited[i], false);
+		}
+	}
+}
+```