int N = fin.nextInt();

　　long[] count = new long[8];

　　count[6] = 0;

　　count[7] = 1;

　　long mod = 1000000007;

　　for (int i = 2; i <= N; ++i) {

　　long[] newCount = new long[8];

　　newCount[0] = (count[0] * 2 + count[1] + count[3]) % mod; newCount[1] = (count[1] * 2 + count[2] + count[5]) % mod; newCount[2] = (count[2] + count[6]) % mod;

　　newCount[3] = (count[3] * 2 + count[4] + count[5]) % mod; newCount[4] = (count[4] + count[7]) % mod;

　　newCount[5] = (count[5] * 2 + count[6] + count[7]) % mod; newCount[6] = 0;

　　newCount[7] = 1;

　　count = newCount;

　　}

　　System.out.println(count[0]);

　　}

　　}

　　5.I’m stuck!

　　import java.util.*;

　　public class Main {

　　public static void main(String[] args) {

　　new Main().run();

　　}

　　public void run() {

　　Scanner fin = new Scanner(System.in);

　　int R = fin.nextInt();

　　int C = fin.nextInt();

　　fin.nextLine();

　　int[][] board = new int[R + 2][C + 2];

　　int rowStart = 0, colStart = 0, rowEnd = 0, colEnd = 0; for (int i = 1; i <= R; ++i) {

　　String line = fin.nextLine();

　　for (int j = 1; j <= C; ++j) {

　　char c = line.charAt(j - 1);

　　switch (c) {

　　case '#': break;

　　case '-': board[i][j] = 5; break;

　　case '|': board[i][j] = 0xA; break;

　　case '+':

　　case 'S':

　　case 'T':

　　board[i][j] = 0xF; break; case '.': board[i][j] = 0x8; break;

　　default: break;

　　}

　　if (c == 'S') {

　　rowStart = i;

　　colStart = j;

　　} else if (c == 'T') {

　　rowEnd = i;

　　colEnd = j;

　　}

　　}

　　}

　　int[] dr = new int[] {0, -1, 0, 1};

　　int[] dc = new int[] {1, 0, -1, 0};

　　// Scan 1: find all cells which can reach T

　　boolean[][] visited = new boolean[R + 2][C + 2]; boolean[][] canReachT = new boolean[R + 2][C + 2]; initVisited(visited);

　　canReachT[rowEnd][colEnd] = true;

　　visited[rowEnd][colEnd] = true;

　　Queue queue = new LinkedList(); queue.add(rowEnd);

　　queue.add(colEnd);

　　while (!queue.isEmpty()) {

　　int r = queue.remove();

　　int c = queue.remove();

　　for (int i = 0; i < 4; ++i) {

　　int nr = r + dr[i];