【HDOJ】1242 Rescue

BFS+优先级队列。

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

#define MAXNUM 205

typedef struct node_st {
    int x, y ,t;
    node_st() {}
    node_st(int xx, int yy, int tt) {
        x = xx; y = yy; t = tt;
    }
    friend bool operator < (node_st a, node_st b) {
        return a.t > b.t;
    }
} node_st;

int n, m;
char map[MAXNUM][MAXNUM];
char visit[MAXNUM][MAXNUM];
int direct[4][2] = {{1,0},{-1,0},{0,-1},{0,1}};

int bfs(int x, int y) {
    priority_queue<node_st> que;
    node_st node;
    int i, t;
    
    que.push(node_st(x, y, 0));
    memset(visit, 0, sizeof(visit));
    visit[x][y] = 1;
    
    while ( !que.empty() ) {
        node = que.top();
        if (map[node.x][node.y] == 'a')
            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 (visit[x][y] || map[x][y]=='#')
                continue;
            if (map[x][y] == 'x')
                que.push(node_st(x,y,t+1));
            else
                que.push(node_st(x,y,t));
            visit[x][y] = 1;
        }
    }

    return -1;
}

int main() {
    int i, j, t;
    int begx, begy;

    while (scanf("%d %d", &n, &m) != EOF) {
        for (i=0; i<n; ++i) {
            scanf("%s", map[i]);
            for (j=0; j<m; ++j) {
                if (map[i][j] == 'r') {
                    begx = i;
                    begy = j;
                }
            }
        }
        t = bfs(begx, begy);
        if (t == -1)
            printf("Poor ANGEL has to stay in the prison all his life.
");
        else
            printf("%d
", t);
    }
    return 0;
}