HDU 1242 （BFS+优先队列）

#include <iostream>
#include <cstdio>
#include <vector>
#include <set>
#include <queue>
#include <iomanip>
#include <cstring>
#include <sstream>
#include <algorithm>
#include <map>
#include <list>

using namespace std;
const int maxn = 200 + 10;
const int dr[] = {0, 0, 1, -1};
const int dc[] = {1, -1, 0, 0};
struct node{
    int r, c, t, d;
    node() { }
    node(int rr, int cc, int tt, int dd) : r(rr), c(cc), t(tt), d(dd) { }
    bool operator < (const node &p) const {
        if(t != p.t)  return t > p.t;
        return d > p.d;
    }
};

char a[maxn][maxn];
node s, e;
int r, c, d[maxn][maxn];

bool is_in(int rr, int cc){
    return rr < r && rr >= 0 && cc >= 0 && cc < c;
}

void bfs(){
    priority_queue<node> q;

    memset(d, -1, sizeof(d));
    d[s.r][s.c] = 0;
    q.push(s);
    while(!q.empty()){
        node u = q.top();  q.pop();

        if(u.r == e.r && u.c == e.c){  printf("%d\n", u.t);  return ;  }
        for(int i = 0; i < 4; ++i){
            int x = u.r + dr[i];
            int y = u.c + dc[i];
            if(is_in(x, y) && a[x][y] == ‘.‘ && d[x][y] < 0){
                d[x][y] = 1 + d[u.r][u.c];
                q.push(node(x, y, u.t+1, u.d+1));
            }
            else if(is_in(x, y) && a[x][y] == ‘x‘ && d[x][y] < 0){
                d[x][y] = 1;
                q.push(node(x, y, u.t+2, u.d+1));
            }
        }
    }

    printf("Poor ANGEL has to stay in the prison all his life.\n");
    return ;
}

int main(){
    while(~scanf("%d %d", &r, &c)){
        for(int i = 0; i < r; ++i)
            scanf("%s", a[i]);

        for(int i = 0; i < r; ++i)
            for(int j = 0; j < c; ++j)
                if(a[i][j] == ‘r‘) { s.r = i;  s.c = j;  s.t = 0;  s.d = 0;  }
                else  if(a[i][j] == ‘a‘) { e.r = i;  e.c = j;  e.t = 0;   a[i][j] = ‘.‘;  }
        bfs();
    }
    return 0;
}