hdu 1429胜利大逃亡(续) / sdut 2193 救基友记3(BFS)

#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <queue>
using namespace std;

int dir[4][2] = { {-1,0},{1,0},{0,-1},{0,1} };
struct node
{
	int x,y;
	int step;
	int sta;
}p[410];

queue <struct node> que;
char map[30][30];
int n,m,t;
int sx,sy;
int mark[30][30][1<<10+10];

void bfs()
{
	memset(mark,0,sizeof(mark));
	while(!que.empty()) que.pop();
	que.push((struct node) {sx,sy,0,0});
	mark[sx][sy][0] = 1;
	while(!que.empty())
	{
		struct node u = que.front();
		que.pop();
		if(u.step >= t)
        {
            printf("-1\n");
            return;
        }
		if(map[u.x][u.y] == '^')
        {
            printf("%d\n",u.step);
            return;
        }
		for(int d = 0; d <= 3; d++)
		{
			int x = u.x+dir[d][0];
			int y = u.y+dir[d][1];
            if(x < 1 || x > n || y < 1 || y > m)
                continue;
			int sta = u.sta;
			int add;
			if(map[x][y] == '.' || map[x][y] == '@' || map[x][y] == '^')
			{
				if(!mark[x][y][sta])
				{
					que.push((struct node){x,y,u.step+1,sta});
					mark[x][y][sta] = 1;
				}
			}

			else if(map[x][y] >= 'a' && map[x][y] <= 'j')
			{
				add = map[x][y]-'a';
				if((sta & (1<<add)) == 0)//注意先判断是否已有这种钥匙，没有再加
                    sta += (1 << add);
				if(!mark[x][y][sta])
				{
					que.push( (struct node) {x,y,u.step+1,sta});
					mark[x][y][sta] = 1;
				}

			}
			else if(map[x][y] >= 'A' && map[x][y] <= 'J')
			{
				add = map[x][y] - 'A';
				if( (sta & (1<<add)) && !mark[x][y][sta])
				{
					que.push((struct node) {x,y,u.step+1,sta});
					mark[x][y][sta] = 1;
				}
			}
		}
	}
	printf("-1\n");
}

int main()
{
	while(~scanf("%d %d %d",&n,&m,&t))
	{
		for(int i = 1; i <= n; i++)
		{
			scanf("%s",map[i]+1);
			for(int j = 1; j <= m; j++)
			{
				if(map[i][j] == '@')
				{
					sx = i;
					sy = j;
				}
			}
		}
		bfs();
	}
	return 0;
}