HDOJ 4308 Saving Princess claire_

简单BFS，遇到'P'时把所有'P'标记，并对所有'P'多向下搜索一步，此时遇到'*'时入队；

BFS的特点：搜到即标记，搜到就判断。

# include <cstdio>

# include <cstring>

# include <queue>



using namespace std;



# define N 5000+5



int n, m, cost;

char g[N][N];

char vis[N][N];



struct pos

{

    int x, y, d;

    pos()

    {

        d = 0;

    }

};

pos st;

queue <pos> Qst;



const int dx[] = {0,0,1,-1};

const int dy[] = {1,-1,0,0};



int bfs(void)

{

    queue <pos> Q;

    Q.push(st);

    vis[st.x][st.y] = 1;

    while (!Q.empty())

    {

        pos cur = Q.front(); Q.pop();

        for (int i = 0; i < 4; ++i)

        {

            pos nst;

            nst.x = cur.x + dx[i];

            nst.y = cur.y + dy[i];

            if (1<=nst.x&&nst.x<=n && 1<=nst.y&&nst.y<=m && !vis[nst.x][nst.y])

            {

                vis[nst.x][nst.y] = 1;

                if (g[nst.x][nst.y] == 'C') return cur.d;

                if (g[nst.x][nst.y] == '#') continue;

                if (g[nst.x][nst.y] == '*') nst.d=cur.d+1,Q.push(nst);

                else if (g[nst.x][nst.y] == 'P')

                {

                    while (!Qst.empty())

                    {

                        nst = Qst.front(); Qst.pop();

                        vis[nst.x][nst.y] = 1;

                        for (int j = 0; j < 4; ++j)

                        {

                            pos pst;

                            pst.x = nst.x + dx[j];

                            pst.y = nst.y + dy[j];

                            if (1<=pst.x&&pst.x<=n && 1<=pst.y&&pst.y<=m && !vis[pst.x][pst.y])

                            {

                                vis[pst.x][pst.y] = 1;

                                if (g[pst.x][pst.y] == 'C') return cur.d;

                                if (g[pst.x][pst.y] == '#') continue;

                                if (g[pst.x][pst.y] == '*') pst.d = cur.d+1, Q.push(pst);

                            }

                        }    

                    }

                }

            }

        }

    }

    return -1;

}



void read(void)

{

    pos tmp;

    while (!Qst.empty()) Qst.pop();

    for (int i = 1; i <= n; ++i)

    {

        scanf("%s", g[i]+1);

        memset(vis[i]+1, 0, sizeof(char)*m);

        for (int j = 1; j <= m; ++j)

        {

            if (g[i][j] == 'P')

            {

                tmp.x = i, tmp.y = j;

                Qst.push(tmp);

             }

             else if (g[i][j] == 'Y')

             {

                 st.x = i, st.y = j;

                 st.d = 0;

              }

         }

     }

}



void solve(void)

{

    int ans = bfs();

    if (ans == -1)

        puts("Damn teoy!");

    else

        printf("%d\n", ans*cost);

}



int main()

{

    while (~scanf("%d%d%d", &n, &m, &cost))

    {

        read();

        solve();

    }

    

    return 0;

}

/**/