HDU2612，简单广搜题

#include<cstdio>
#include<iostream>
#include<cstdlib>
#include<cstring>
#include<queue>
using namespace std;
struct node
{
int x,y,step;
};//记录点的坐标以及到该点的时间
int n,m;
char ch[209][209];
int dir[4][2] = {0,-1,-1,0,0,1,1,0};
int vis[209][209],num[209][209];//vis标记数组，num记录到@的总时间
bool is_ok(node a)//判断是否越界
{
return a.x >= 0 && a.x < n && a.y >= 0 && a.y < m;
}
void bfs(int x,int y)
{
node s,t,ne;
int i;
s.x = x;
s.y = y;
s.step = 0;
queue<node>q;
while (!q.empty())
q.pop();
vis[x][y] = 1;
q.push(s);
while (!q.empty())
{
t = q.front();
q.pop();
for (i = 0; i < 4; ++i)
{
ne.x = t.x + dir[i][0];
ne.y = t.y + dir[i][1];
ne.step = t.step + 1;
if (is_ok(ne) && ch[ne.x][ne.y] != '#' && !vis[ne.x][ne.y])
//Y,M,和@都可以走
{
vis[ne.x][ne.y] = 1;
q.push(ne);
if (ch[ne.x][ne.y] == '@')
{
num[ne.x][ne.y] += ne.step;//这里是+=，不是=，因为这点是@，记录的是两人到这的总时间
}
}
}
}
}
int main()
{
int yx,yy,mx,my,i,j;
while (~scanf("%d%d",&n,&m))
{
for (i = 0; i < n; ++i)
{
getchar();
for (j = 0; j < m; ++j)
{
scanf("%c",&ch[i][j]);
if (ch[i][j] == 'Y')
{
yx = i;
yy = j;
}
else if (ch[i][j] == 'M')
{
mx = i;
my = j;
}
}
}
memset(vis,0,sizeof(vis));
memset(num,0,sizeof(num));
bfs(yx,yy);
memset(vis,0,sizeof(vis));
bfs(mx,my);
int ans = 9999999;
for (i = 0; i < n; ++i)//找最小总时间
{
for (j = 0; j < m; ++j)
{
if (num[i][j] != 0 && ans > num[i][j])
ans = num[i][j];
}
}
printf("%d\n",ans*11);
}
return 0;
}