[USACO11OPEN]玉米田迷宫Corn Maze

题面

bfs

注意事项

①鬼畜死循环TLE

②装置不成对

③本来最优解被传送门的#给盖住了，必须新开一个数组来存

④步数没有+对，因为遇到传送门是跳着走的

#include <cstdio>
#include <iostream>
#include <queue>
#include<map>
using namespace std;
int n,m;
char a[302][302];
char usual[302][302];
char special[302][302];
int dx[4] = {0,1,0,-1};
int dy[4] = {1,0,-1,0};
struct qwq {
    int my_x1,my_x2,my_y1,my_y2;
    int flag;
};
map<char,qwq> cs;
int be_x,be_y;struct Pos {
    int x,y,step;
};
queue<Pos> bfs;
int main() {
    cin>>n>>m;
    for(int i=1; i<=n; i++) {
        for(int j=1; j<=m; j++) {
            cin>>a[i][j];
            special[i][j]=a[i][j];
            usual[i][j]=a[i][j];
            if(a[i][j]>='A'&&a[i][j]<='Z') {
                if(cs[a[i][j]].flag==0) {
                    cs[a[i][j]].my_x1=i;
                    cs[a[i][j]].my_y1=j;
                    cs[a[i][j]].flag++;
                } else {
                    cs[a[i][j]].my_x2=i;
                    cs[a[i][j]].my_y2=j;
                    cs[a[i][j]].flag++;
                }
                special[i][j]=a[i][j];
            } else if(a[i][j]=='@') {
                be_x=i;
                be_y=j;
            }
        }
    }
    bfs.push({be_x,be_y,0});

    while(!bfs.empty()) {
        Pos head = bfs.front();
        for(int i = 0; i < 4; i++) {
            int tx = head.x+dx[i], ty = head.y+dy[i];
            if(a[tx][ty]=='=') {
                cout<<head.step+1<<endl;
                return 0;
            } else if(a[tx][ty]>='A'&&a[tx][ty]<='Z' && special[tx][ty]!='#' ) {
                if(cs[a[tx][ty]].flag==1) {
                    special[tx][ty]='#';
                    bfs.push({tx,ty,head.step+1});
                    continue;
                }
                special[tx][ty]='#';
                char flag2=a[tx][ty];
                if(cs[flag2].my_x1==tx && cs[flag2].my_y1 == ty) {
                    tx=cs[flag2].my_x2;
                    ty=cs[flag2].my_y2;
                } else {
                    tx=cs[flag2].my_x1;
                    ty=cs[flag2].my_y1;
                }
                bfs.push({tx,ty,head.step+1});
            } else if(a[tx][ty]=='.' && usual[tx][ty]=='.') {
                usual[tx][ty]='#';
                bfs.push({tx,ty,head.step+1});
            }
        }
        bfs.pop();
    }
    return 0;
}