题意：

求从进入点到出口，分别按靠左边，右边和最短距离到达出口所学要的步数。

思路：

坐标问题弄的稀里糊涂的，引用 discuss 里面的思路吧：

向左：依左上右下的顺序针方向走。根据上一个来的方向判断当前坐标开始走的方向，按顺时针走即可，回溯时经过的格子数也要增加，并且方向要反向向右：依右上左下的逆时针方向走即可最短是普通的 BFS

 

#include 
    
     #include 
     
      #include 
      
       using namespace std;const int MAXN = 50;struct ST {
         int x, y, step;    ST(int _x, int _y, int _s) : x(_x), y(_y), step(_s) {}};char grid[MAXN][MAXN];bool vis[MAXN][MAXN];int dir[4][2] = {
     {
     0,-1}, {
     -1,0}, {
     0,1}, {
     1,0}};int ans;bool lhsDfs(int x, int y, int o, int step) {
         if (grid[x][y] == 'E') {
             ans = step;         return true;    }    for (int i = o; i < o + 4; ++i) {
             int newx = x + dir[i%4][0];        int newy = y + dir[i%4][1];        if (grid[newx][newy] != '#') {
                 if (lhsDfs(newx, newy, (i-1+4)%4, step+1))                return true;        }    }    return false;}bool rhsDfs(int x, int y, int o, int step) {
         if (grid[x][y] == 'E') {
             ans = step;         return true;    }    for (int i = o + 4; i > o; --i) {
             int newx = x + dir[i%4][0];        int newy = y + dir[i%4][1];        if (grid[newx][newy] != '#') {
                 if (rhsDfs(newx, newy, (i+1)%4, step+1))                return true;        }    }    return false;}int bfs(int x, int y) {
         deque
       
         q;    q.push_back(ST(x, y, 1));    vis[x][y] = true;    while (!q.empty()) {
             ST s = q.front();        q.pop_front();        if (grid[s.x][s.y] == 'E')             return s.step;        for (int i = 0; i < 4; ++i) {
                 int newx = s.x + dir[i][0];            int newy = s.y + dir[i][1];            if (grid[newx][newy] != '#' && !vis[newx][newy]) {
                     vis[newx][newy] = true;                q.push_back(ST(newx, newy, s.step + 1));               }        }    }}int main(){
         int cases;    scanf("%d", &cases);    while (cases--) {
             int row, col;        scanf("%d %d", &col, &row);        memset(grid, '#', sizeof(grid));        for (int i = 1; i <= row; ++i)            scanf("%s", &grid[i][1]);        int x, y;        for (int i = 1; i <= row; ++i)             for (int j = 1; j <= col; ++j)                if (grid[i][j] == 'S') x = i, y = j;        lhsDfs(x, y, 0, 1);        printf("%d ", ans);        rhsDfs(x, y, 0, 1);        printf("%d ", ans);        memset(vis, false, sizeof(vis));        printf("%d\n", bfs(x, y));    }    return 0;}