最简单的BFS，只不过每个点带上颜色和方向即可，注意题目说的是左转和右转90°，转向的时候是原地不动

#include <cstdio>
#include <cstring>
#include <algorithm>
#include <queue>
#define MAXN 30
using namespace std;
#define NORTH 0
#define SOUTH 1
#define WEST 2
#define EAST 3
#define INF 1000000
char mp[MAXN][MAXN];
int n,m;
struct Point {
    int x,y,dir,step,color;
};
int dir[4][3][2] = {{{-1,0},{0,0},{0,0}},{{1,0},{0,0},{0,0}},{{0,-1},{0,0},{0,0}},{{0,1},{0,0},{0,0}}};
bool used[MAXN][MAXN][4][5];
int sx,sy,tx,ty;
queue<Point> q;

void clear_q() {
    while(!q.empty()) q.pop();
}

int cal_dir(int dir,int i) {
    if(dir==NORTH&&i==0) return NORTH;  
    if(dir==NORTH&&i==1) return WEST;
    if(dir==NORTH&&i==2) return EAST;
    if(dir==SOUTH&&i==0) return SOUTH;
    if(dir==SOUTH&&i==1) return EAST;
    if(dir==SOUTH&&i==2) return WEST;
    if(dir==WEST&&i==0) return WEST;
    if(dir==WEST&&i==1) return SOUTH;
    if(dir==WEST&&i==2) return NORTH;
    if(dir==EAST&&i==0) return EAST;
    if(dir==EAST&&i==1) return NORTH;
    if(dir==EAST&&i==2) return SOUTH;
}

int main() {
    int kase = 1;
    while(scanf("%d%d",&n,&m) != EOF) {
        memset(used,0,sizeof(used));
        if(n==0&&m==0) break;
        if(kase!=1) printf("\n");
        for(int i = 0;i < n;i++) scanf("%s",mp+i);
        for(int i = 0;i < n;i++)
            for(int j = 0;j < m;j++) {
                if(mp[i][j] == 'S') {
                    sx = i;
                    sy = j;
                }
                if(mp[i][j] == 'T') {
                    tx = i;
                    ty = j;
                }
            }

        clear_q();
        q.push((Point){sx,sy,NORTH,0,3});
        used[sx][sy][NORTH][3] = true;
        int res = INF;
        while(!q.empty()) {
            Point cur = q.front();
            q.pop();
            if(cur.x == tx && cur.y == ty && cur.color == 3) {
                res = cur.step;
                clear_q();
                break;
            }
            for(int i = 0;i < 3;i++) {
                int xx = cur.x+dir[cur.dir][i][0];
                int yy = cur.y+dir[cur.dir][i][1];
                if(xx<0||xx>=n||yy<0||yy>=m) continue;
                if(mp[xx][yy] == '#') continue;
                int dir = cal_dir(cur.dir,i);
                int color = (cur.color+4)%5;
                if(i!=0) {
                    color = cur.color;
                }
                if(used[xx][yy][dir][color]) continue;
                q.push((Point){xx,yy,dir,cur.step+1,color});
                used[xx][yy][dir][color] = true;
            }
        }
        printf("Case #%d\n",kase++);
        if(res == INF) {
            printf("destination not reachable\n");
        } else {
            printf("minimum time = %d sec\n",res);
        }
        
    }

    return 0;
}