【HDOJ】1429 胜利大逃亡(续)

BFS+状态压缩，做了很多状态压缩了。今晚把八数码问题给搞定了。

#include <iostream>
#include <queue>
#include <cstring>
#include <cstdio>
using namespace std;

typedef struct node_st {
    int x, y, t;
    int key;
    node_st() {}
    node_st(int xx, int yy, int tt, int kk) {
        x = xx; y = yy; t = tt; key = kk;
    }
} node_st;

char map[25][25];
char visit[1<<10][25][25];
int direct[4][2] = {{-1,0},{1,0},{0,-1},{0,1}};
int n, m, time;

int bfs(int bx, int by) {
    int x, y, key, t;
    int i, tmp;
    queue<node_st> que;
    node_st node;

    memset(visit, 0, sizeof(visit));
    visit[bx][by][0] = 1;
    que.push(node_st(bx,by,0,0));

    while ( !que.empty() ) {
        node = que.front();
        if (node.t >= time)
            return -1;
        if (map[node.x][node.y] == '^')
            return node.t;
        que.pop();
        t = node.t + 1;
        for (i=0; i<4; ++i) {
            x = node.x + direct[i][0];
            y = node.y + direct[i][1];
            if (x<0 || x>=n || y<0 || y>=m)
                continue;
            if (map[x][y]>='a' && map[x][y]<='j')
                key = node.key | (1<<(map[x][y]-'a'));
            else
                key = node.key;
            if (visit[key][x][y] || map[x][y]=='*')
                continue;
            if (map[x][y]>='A' && map[x][y]<='J') {
                tmp = (1<<(map[x][y]-'A')) & key;
                if ( !tmp )
                    continue;
            }
            que.push(node_st(x,y,t,key));
            visit[key][x][y] = 1;
        }
    }

    return -1;
}

int main() {
    int bx, by;
    int i, j;

    while (scanf("%d %d %d", &n, &m, &time) != EOF) {
        for (i=0; i<n; ++i) {
            scanf("%s", map[i]);
            for (j=0; j<m; ++j) {
                if (map[i][j] == '@') {
                    bx = i;
                    by = j;
                }
            }
        }
        i = bfs(bx, by);
        printf("%d\n", i);
    }

    return 0;
}