uva 816 带方向的bfs

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题意：

以下摘自小紫：

给一个9*9的迷宫，输入起点、离开起点时的朝向和终点，求一条最短路。（多解任意输出）

进入一个交叉点的方向（用NEWS这4个字母分别表示北东西南，即上右左下）不同，允许出去的方向也不同。

如图：

解析：

首先弄懂在每个点的状态有哪些：位置（x，y）朝向d，以此来建立节点，并且以此来建立bfs的状态step；

然后是方向dir与转弯turn的转换；

接着就bfs，然后打印路径，为了防止栈溢出，改用了循环，vector来保存路径；

有点坑爹的地方是判断外界要用[1,9]，而我开始的时候直接判最大的输入了。

代码：

#pragma comment(linker, "/STACK:1677721600")#include <map>#include <set>#include <cmath>#include <queue>#include <stack>#include <vector>#include <cstdio>#include <cstdlib>#include <cstring>#include <climits>#include <cassert>#include <iostream>#include <algorithm>#define pb push_back#define mp make_pair#define LL long long#define lson lo,mi,rt<<1#define rson mi+1,hi,rt<<1|1#define Min(a,b) ((a)<(b)?(a):(b))#define Max(a,b) ((a)>(b)?(a):(b))#define mem(a,b) memset(a,b,sizeof(a))#define FIN freopen("in.txt", "r", stdin)#define FOUT freopen("out.txt", "w", stdout)#define rep(i,a,b) for(int i=(a); i<=(b); i++)#define dec(i,a,b) for(int i=(a); i>=(b); i--)using namespace std;const int mod = 1e9 + 7;const double eps = 1e-8;const double ee = exp(1.0);const int inf = 0x3f3f3f3f;const double pi = acos(-1.0);int readT(){    char c;    int ret = 0,flg = 0;    while(c = getchar(), (c < '0' || c > '9') && c != '-');    if(c == '-') flg = 1; else ret = c ^ 48;    while( c = getchar(), c >= '0' && c <= '9') ret = ret * 10 + (c ^ 48);    return flg ? - ret : ret;}LL readTL(){    char c;    int flg = 0;    LL ret = 0;    while(c = getchar(), (c < '0' || c > '9') && c != '-');    if(c == '-') flg = 1; else ret = c ^ 48;    while( c = getchar(), c >= '0' && c <= '9') ret = ret * 10 + (c ^ 48);    return flg ? - ret : ret;}const int maxX = 9 + 10;const int maxY = 9 + 10;const int maxD = 4 + 10;const int maxT = 3 + 10;int dir[][2] = {{-1, 0}, {0, 1}, {1, 0}, {0, -1}};struct Node{    int x, y, d;    Node(int _x = 0, int _y = 0, int _d = 0)    {        x = _x;        y = _y;        d = _d;    }};bool maze[maxX][maxY][maxD][maxT];int step[maxX][maxY][maxD];Node path[maxX][maxY][maxD];int getDir(char c){    if (c == 'N')        return 0;    if (c == 'E')        return 1;    if (c == 'S')        return 2;    if (c == 'W')        return 3;}int getTurn(char c){    if (c == 'F')        return 0;    if (c == 'L')        return 1;    if (c == 'R')        return 2;}Node go(Node u, int turn){    int d = u.d;    if (turn == 1)        d = (d + 3) % 4;    if (turn == 2)        d = (d + 1) % 4;    return Node(u.x + dir[d][0], u.y + dir[d][1], d);}bool inMaze(int x, int y){    if (1 <= x && x <= 9 && 1 <= y && y <= 9)        return true;    return false;}void printPath(Node now){    vector<Node> nodes;    while (true)    {        nodes.pb(now);        if (step[now.x][now.y][now.d] == 0)            break;        now = path[now.x][now.y][now.d];    }    nodes.pb(Node(now.x - dir[now.d][0], now.y - dir[now.d][1], now.d));    int cnt = 0;    for (int i = nodes.size() - 1; i >= 0; i--)    {        if (cnt % 10 == 0)            printf(" ");        printf(" (%d,%d)", nodes[i].x, nodes[i].y);        if (++cnt % 10 == 0)            puts("");    }    if (nodes.size() % 10 != 0)        puts("");}bool bfs(Node st, Node ed){//    cout << st.x << " " << st.y << " " << st.d << endl;    st.x = st.x + dir[st.d][0];    st.y = st.y + dir[st.d][1];    mem(step, -1);    step[st.x][st.y][st.d] = 0;//    cout << st.x << " " << st.y << " " << st.d << endl;    queue<Node> q;    q.push(st);    while (!q.empty())    {        Node now = q.front();        q.pop();        if (now.x == ed.x && now.y == ed.y)        {             printPath(now);//            cout << "ok" << endl;            return true;        }        for (int i = 0; i < 3; i++)        {            Node nxt = go(now, i);            if (inMaze(nxt.x, nxt.y) && maze[now.x][now.y][now.d][i] && step[nxt.x][nxt.y][nxt.d] == -1)            {                step[nxt.x][nxt.y][nxt.d] = step[now.x][now.y][now.d] + 1;                path[nxt.x][nxt.y][nxt.d] = now;                q.push(nxt);            }        }    }    return false;}int main(){    #ifdef LOCAL    FIN;    #endif // LOCAL    string name;    string eof = "END";    while (cin >> name)    {        if (name == eof)            break;        mem(maze, false);        int stX = readT();        int stY = readT();        char c[2];        scanf("%s", c);        int edX = readT();        int edY = readT();//    cout << stX << " " << stY << endl;//    cout << edX << " " << edY << endl;        int x, y;        string mapDir;        while (scanf("%d", &x) && x)        {            scanf("%d", &y);            while (cin >> mapDir)            {                if (mapDir == "*")                    break;                int len = mapDir.length();                int d = getDir(mapDir[0]);                for (int i = 1; i < len; i++)                {                    int t = getTurn(mapDir[i]);                    maze[x][y][d][t] = true;//                    cout << "x: " << x << "  y: " << y << "  d: " << d << "  t: " << t << endl;                }            }        }        cout << name << endl;        bool ok = bfs(Node(stX, stY, getDir(c[0])), Node(edX, edY, 0));        if (!ok)        {            puts("  No Solution Possible");        }    }    return 0;}

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