USACO 2011 Open Silver 1.Corn Maze (bfs)

典型的bfs我還做了這麼半天。。。

注意：本題是強制轉換！！！

#include<stdio.h>
#include<string.h>
#include<queue>
#include<algorithm>
using namespace std;
struct node
{
    int x1,x2,y1,y2;
}edge[30];
int dir[4][2]={
    1,0,
    0,1,
    -1,0,
    0,-1
};
int n,m;
char map[500][500];
int sx,sy,tx,ty;
int dis[500][500];
int tox[500][500],toy[500][500];
int vis[500][500];
int inside(int x,int y)
{
    if(x>=0&&x<n&&y>=0&&y<m)return 1;
    return 0;
}
int bfs()
{
    memset(dis,0x3f,sizeof(dis));
    queue<int>X;
    queue<int>Y;
    X.push(sx);
    Y.push(sy);
    dis[sx][sy]=0;
    vis[sx][sy]=1;
    while(!X.empty())
    {
        int ux=X.front();
        int uy=Y.front();
        X.pop();
        Y.pop();
        vis[ux][uy]=0;
        if(ux==tx&&uy==ty)
        {
        	return dis[ux][uy];
        }
        for(int i=0;i<4;i++)
        {
            int vx=ux+dir[i][0];
            int vy=uy+dir[i][1];
            if(inside(vx,vy)==0)continue;
            if(map[vx][vy]=='.'||map[vx][vy]=='=')
            {
                if(dis[vx][vy]>dis[ux][uy]+1)
                {
                    dis[vx][vy]=dis[ux][uy]+1;
                    X.push(vx);
                    Y.push(vy);
                }
            }else if(map[vx][vy]>='A'&&map[vx][vy]<='Z')
            {
            	if(dis[tox[vx][vy]][toy[vx][vy]]>dis[ux][uy]+1)//直接跳到另一點，這一點不算。
            	{
	            	dis[tox[vx][vy]][toy[vx][vy]]=dis[ux][uy]+1;
	            	if(vis[tox[vx][vy]][toy[vx][vy]]==0)
	            	{
	            		vis[tox[vx][vy]][toy[vx][vy]]=1;
	            		X.push(tox[vx][vy]);
            			Y.push(toy[vx][vy]);
	            	}
	            }
            }
        }
    }
    return 0;
}
int main()
{
    memset(edge,-1,sizeof(edge));
    scanf("%d %d",&n,&m);
    for(int i=0;i<n;i++)
    {
        scanf("%s",map[i]);
        for(int j=0;j<m;j++)
        {
            if(map[i][j]=='=')
            {
                tx=i;
                ty=j;
            }else if(map[i][j]=='@')
            {
                sx=i;
                sy=j;
            }else if(map[i][j]>='A'&&map[i][j]<='Z')
            {
                int t=map[i][j]-'A';
                if(edge[t].x1==-1)
                {
                    edge[t].x1=i;
                    edge[t].y1=j;
                }else
                {
                    edge[t].x2=i;
                    edge[t].y2=j;
                    tox[edge[t].x1][edge[t].y1]=edge[t].x2;
                    toy[edge[t].x1][edge[t].y1]=edge[t].y2;
                    tox[edge[t].x2][edge[t].y2]=edge[t].x1;
                    toy[edge[t].x2][edge[t].y2]=edge[t].y1;
                }
            }
        }
    }
    printf("%d",bfs());
}