走迷宫（bfs， 最短路）

Input

10 10
#S######.#
......#..#
.#.##.##.#
.#........
##.##.####
....#....#
.#######.#
....#.....
.####.###.
....#...G#

---

Output

22

---

代码：

#include<iostream>
#include<cstring>
#include<queue>
using namespace std;
typedef pair<int, int> P;
queue<P> pos;
const int maxn = 100;
char maze[maxn][maxn];
using namespace std;
int N, M;   //N, M分别代表行数和列数
int bx = -1, by = -1, ex = -1, ey = -1;     //代表起点和终点
int d[maxn][maxn];  //储存各个点到起点的距离
int dx[] = {1, 0, -1, 0};
int dy[] = {0, 1, 0, -1};   //遍历四个方向
int vis[maxn][maxn];
const int INF = 0x3f3f3f3f;
int bfs()
{
    pos.push(P(bx, by));
    memset(vis, 0, sizeof(vis));
    while(pos.size())
    {
        P p = pos.front();
        pos.pop();
        if(p.first == ex && p.second == ey)
            break;
        vis[p.first][p.second] = 1;
        //遍历四个方向
        for(int i = 0; i < 4; i++)
        {

                int curx = p.first + dx[i], cury = p.second + dy[i];
                if(curx >= 0 && curx < N && cury >= 0 && cury < M && !vis[curx][cury] && maze[curx][cury] != '#')   //说明它还未放入过栈中
                {
                    vis[curx][cury] = 1;        //表示已经访问过
                    pos.push(P(curx, cury));
                    d[curx][cury] = d[p.first][p.second] + 1;
                }

        }
    }
    return d[ex][ey];

}
int main()
{
    cin >> N >> M;
    for(int i = 0; i < N; i++)
        cin >> maze[i];
    for(int i = 0; i < N; i++)
    {
        for(int j = 0; j < M; j++)
        {
            if(maze[i][j] == 'S')
            {
                bx = i;
                by = j;
                d[i][j] = 0;
            }
            else
                d[i][j] = INF;
            if(maze[i][j] == 'G')
            {
                ex = i;
                ey = j;
            }
        }
    }
    int ans = bfs();
    if(ans != INF)
        cout << ans << endl;
    else
        cout << "NO way!" << endl;

}