第六章部分例题

uva 816

#include <iostream>
#include <cstdio>
#include <cstring>
#include <queue>
#include <vector>
#include <sstream>

using namespace std;

struct Node
{    
    int r,c,dir;
    
    Node(int rx,int cx,int dirx):r(rx),c(cx),dir(dirx){}
    Node(){}
};


const int maxn=11;
int has_edge[maxn][maxn][4][3],d[maxn][maxn][4];
Node p[maxn][maxn][4];

int r0,c0,r1,c1,r2,c2;
char dir0,dir1;

const char* dirs="NESW";
const char* turns="FLR";

int dir_id(char dir) { return strchr(dirs,dir)-dirs;}
int turn_id(char turn) { return strchr(turns,turn)-turns;}

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

Node walk(Node n,int i)
{
    int dir=n.dir;

    if(i==1) dir=(dir+3)%4;
    if(i==2) dir=(dir+1)%4;

    return Node(n.r+dr[dir],n.c+dc[dir],dir);
}

void print_ans(Node node)
{
    vector<Node> nodes;

    for(;;)
    {

        int r=node.r;
        int c=node.c;
        int dir=node.dir;

        nodes.push_back(node);

        if(d[r][c][dir]==0) break;

        node=p[r][c][dir];

    }

    int cnt=0;
    for(int i=nodes.size()-1;i>=0;i--)
    {
        if(cnt%10==0) printf(" ");
        printf(" (%d,%d)",nodes[i].r,nodes[i].c);
        if(++cnt %10==0) printf("
");
    }

    if(nodes.size()%10!=0) printf("
");
}

void bfs()
{    
    
    Node u=Node(r1,c1,dir_id(dir1));
    p[r1][c1][dir_id(dir1)]=Node(r0,c0,dir_id(dir0));
    d[r0][c0][dir_id(dir0)]=0;
    d[r1][c1][dir_id(dir1)]=1;

    queue<Node> q;

    q.push(u);

    while(!q.empty())
    {
        Node newn=q.front();
        q.pop();

        int r,c,dir;

        r=newn.r;
        c=newn.c;
        dir=newn.dir;

        if(r==r2 && c==c2) { print_ans(newn); return;}

        for(int i=0;i<3;i++)
        {
            if(has_edge[r][c][dir][i])
            {
                Node nextn=walk(newn,i);

                if(d[nextn.r][nextn.c][nextn.dir]<0)
                {
                    d[nextn.r][nextn.c][nextn.dir]=d[newn.r][newn.c][newn.dir]+1;
                    p[nextn.r][nextn.c][nextn.dir]=newn;
                    q.push(nextn);
                }
            }
        }

    }

    printf("NO SOLUTIONS
");
}

int main()
{
    string name;

    while(cin>>name && name!="END")
    {

        memset(p,0,sizeof(p));
        memset(has_edge,0,sizeof(has_edge));
        memset(d,-1,sizeof(d));

        cin>>r0>>c0>>dir0;
        cin>>r2>>c2;

/*
        cout<<"r0="<<r0<<endl;
        cout<<"c0="<<c0<<endl;
        cout<<"dir0="<<dir0<<endl;
        cout<<"r2="<<r2<<endl;
        cout<<"c2="<<c2<<endl;
        
*/
        r1=r0+dr[dir_id(dir0)];
        c1=c0+dc[dir_id(dir0)];
        dir1=dir0;

/*
        cout<<"r1="<<r1<<endl;
        cout<<"c1="<<c1<<endl;

*/

        string line;

        getchar();                            //c2后还有个回车所以要先接受
        while(getline(cin,line) && line!="0")
        {
            //cout<<"line:"<<line<<endl;

            stringstream ss(line);

            int r,c;
            ss>>r>>c;

            string str;
            while(ss>>str && str[0]!='*')
            {

                //cout<<"str:"<<str<<endl;
                int dir=dir_id(str[0]);

                for(int i=1;i<str.size();i++)
                {
                    int turn=turn_id(str[i]);

                    has_edge[r][c][dir][turn]=1;
                }

            }

            ss.clear();
        }

        cout<<name<<endl;
        bfs();
    }

    return 0;
}