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| 1 | +import java.io.BufferedReader; |
| 2 | +import java.io.IOException; |
| 3 | +import java.io.InputStreamReader; |
| 4 | +import java.util.StringTokenizer; |
| 5 | + |
| 6 | +public class SB_18430 { |
| 7 | + static int N,M; |
| 8 | + static int[][] board; |
| 9 | + static int[][] wings = { |
| 10 | + {0, -1, 1, 0}, |
| 11 | + {-1, 0, 0, -1}, |
| 12 | + {-1, 0, 0, 1}, |
| 13 | + {0, 1, 1, 0} |
| 14 | + }; |
| 15 | + static int ans = 0; |
| 16 | + |
| 17 | + private static void dfs(int x, int y, int val, boolean[][] visited) { |
| 18 | + if(x==N) { // 모든 칸 탐색 |
| 19 | + ans = Math.max(ans, val); |
| 20 | + return; |
| 21 | + } |
| 22 | + |
| 23 | + int nx = (y+1 == M) ? x+1 : x; // 다음 위치, 다음 행으로 이동 or 열로 이동 |
| 24 | + int ny = (y+1 == M) ? 0 : y+1; |
| 25 | + |
| 26 | + if (visited[x][y]){ |
| 27 | + dfs(nx, ny, val, visited); |
| 28 | + return; |
| 29 | + } |
| 30 | + |
| 31 | + visited[x][y] = true; |
| 32 | + for (int[] w : wings){ |
| 33 | + int lx = x + w[0]; // 날개 좌표 |
| 34 | + int ly = y + w[1]; |
| 35 | + int rx = x + w[2]; |
| 36 | + int ry = y + w[3]; |
| 37 | + |
| 38 | + if (!isValid(lx, ly) || !isValid(rx, ry) || visited[lx][ly] || visited[rx][ry]) continue; |
| 39 | + |
| 40 | + visited[lx][ly] = true; |
| 41 | + visited[rx][ry] = true; |
| 42 | + |
| 43 | + int curVal = val + board[x][y]*2 + board[lx][ly] + board[rx][ry]; |
| 44 | + dfs(nx, ny, curVal, visited); |
| 45 | + visited[lx][ly] = false; |
| 46 | + visited[rx][ry] = false; |
| 47 | + } |
| 48 | + visited[x][y] = false; |
| 49 | + |
| 50 | + // 부메랑 안만드는 경우 |
| 51 | + dfs(nx, ny, val, visited); |
| 52 | + |
| 53 | + } |
| 54 | + |
| 55 | + private static boolean isValid(int x, int y){ |
| 56 | + return 0<=x && x<N && 0<=y && y<M; |
| 57 | + } |
| 58 | + |
| 59 | + public static void main(String[] args) throws IOException { |
| 60 | + BufferedReader br = new BufferedReader(new InputStreamReader(System.in)); |
| 61 | + StringTokenizer st = new StringTokenizer(br.readLine()); |
| 62 | + |
| 63 | + N = Integer.parseInt(st.nextToken()); |
| 64 | + M = Integer.parseInt(st.nextToken()); |
| 65 | + |
| 66 | + board = new int[N][M]; |
| 67 | + for (int i = 0; i < N; i++) { |
| 68 | + st = new StringTokenizer(br.readLine()); |
| 69 | + for (int j = 0; j < M; j++) { |
| 70 | + board[i][j] = Integer.parseInt(st.nextToken()); |
| 71 | + } |
| 72 | + } |
| 73 | + |
| 74 | + boolean[][] visited = new boolean[N][M]; |
| 75 | + dfs(0, 0, 0, visited); |
| 76 | + System.out.println(ans); |
| 77 | + } |
| 78 | +} |
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