poj2688 Cleaning Robot 简单BFS+DFS

#include <cstdio>
#include <iostream>
#include <algorithm>
#include <cstring>
#include <queue>
#include <vector>
#include <cmath>
using namespace std;
#define pb(a) push_back(a)
struct node
{
int x,y,n;
};
int dx[]={0,1,-1,0};
int dy[]={1,0,0,-1};
vector<node>dirt;
node rob;
int dis[500][500];
int m,n,lab;
char tab[30][30];
int label[30][30];
int vis[30][30],ans;
bool judge(int x,int y)
{
if(x>0&&x<=n&&y>0&&y<=m)
{
return true;
}
return false;
}
bool bfs(node st)
{
queue<node>q;
memset(vis,0,sizeof(vis));
node tmp,cur;
int now,xx,yy,x,y,tot,tt;
vis[st.x][st.y]=1;
q.push(st);
while(!q.empty())
{
tmp=q.front();
q.pop();
x=tmp.x;
y=tmp.y;
for(int i=0;i<4;i++)
{
xx=x+dx[i];
yy=y+dy[i];
if(!judge(xx,yy)) continue;
if(vis[xx][yy]||tab[xx][yy]=='x') continue;
vis[xx][yy]=vis[x][y]+1;
cur.x=xx;
cur.y=yy;
q.push(cur);
}
}
}
int use[500];
void dfs(int now,int sum,int num)
{
if(sum>ans)
{
return;
}
if(num==lab-1)
{
ans=min(ans,sum);
return ;
}
for(int i=2;i<=lab;i++)
{
if(use[i]) continue;
use[i]=1;
dfs(i,sum+dis[now][i],num+1);
use[i]=0;
}
}
void solve()
{
bfs(rob);
ans=0x3f3f3f3f;
for(int i=0;i<dirt.size();i++)
{
dis[dirt[i].n][1]=dis[1][dirt[i].n]=vis[dirt[i].x][dirt[i].y]-1;
if(dis[1][dirt[i].n]<=0)
{
printf("-1\n");
return;
}
}
int now;
for(int j=0;j<dirt.size();j++)
{
now=dirt[j].n;
bfs(dirt[j]);
for(int i=0;i<dirt.size();i++)
{
dis[dirt[i].n][now]=dis[now][dirt[i].n]=vis[dirt[i].x][dirt[i].y]-1;
}
}
dfs(1,0,0);
printf("%d\n",ans);
}
int main()
{
while(scanf("%d%d",&m,&n))
{
if(n+m==0)
{
break;
}
lab=1;
node tmp;
dirt.clear();
memset(label,0,sizeof(label));
memset(dis,0,sizeof(dis));
memset(use,0,sizeof(use));
for(int i=1;i<=n;i++)
{
scanf("%s",tab[i]+1);
for(int j=1;j<=m;j++)
{
if(tab[i][j]=='o')
{
rob.x=i;
rob.y=j;
rob.n=1;
label[i][j]=1;
}
if(tab[i][j]=='*')
{
lab++;
tmp.x=i;
tmp.y=j;
tmp.n=lab;
label[i][j]=lab;
dirt.pb(tmp);
}
}
}
solve();
}
return 0;
}
/*
7 5
.......
.o...*.
.......
.*...*.
.......
15 13
.......x.......
...o...x....*..
.......x.......
.......x.......
.......x.......
...............
xxxxx.....xxxxx
...............
.......x.......
.......x.......
.......x.......
..*....x....*..
.......x.......
10 10
..........
..o.......
..........
..........
..........
.....xxxxx
.....x....
.....x.*..
.....x....
.....x....
0 0

8
49
-1

*/