hdu1242(bfs+优先队列)

题目链接：题目链接

题意：X代表卫兵，a代表终点，r代表起始点，.代表路，#代表墙
     路花费一秒，x花费两秒
     问到达终点的最少时间

思路：bfs 优先队列存储走的步数  

c++代码

#include 
#include 
#include 
using namespace std;

struct node
{
    int x,y,step;
    friend bool operator<(node n1,node n2)
    {
        return n2.step=n || y>=m || !vis[x][y] || map[x][y] == '#')
        return 1;
    return 0;
}

int bfs()
{
    int i;
    priority_queue Q;
    node a,next;
    a.x = x1;
    a.y = y1;
    a.step = 0;
    Q.push(a);
    vis[x1][y1] = 0;
    while(!Q.empty())
    {
        a = Q.top();
        Q.pop();
        if(a.x == x2 && a.y == y2)
            return a.step;
        for(i = 0; i<4; i++)
        {
            next = a;
            next.x+=to[i][0];
            next.y+=to[i][1];
            if(check(next.x,next.y))//判断
                continue;
            next.step++;
            if(map[next.x][next.y] == 'x')//卫兵处多花费了一秒
                next.step++;
            if(vis[next.x][next.y]>=next.step)//存入最小时间
            {
                vis[next.x][next.y] = next.step;
                Q.push(next);
            }
        }
    }
    return 0;
}

int main()
{
    int i,j;
    while(~scanf("%d%d",&n,&m))
    {
        for(i = 0; i