bzoj1627[Usaco2007 Dec]穿越泥地*

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <algorithm>
 4 #include <queue>
 5 #define inc(i,j,k) for(int i=j;i<=k;i++)
 6 #define maxn 1010
 7 using namespace std;
 8 
 9 inline int read(){
10     char ch=getchar(); int f=1,x=0;
11     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1; ch=getchar();}
12     while(ch>=‘0‘&&ch<=‘9‘)x=x*10+ch-‘0‘,ch=getchar();
13     return f*x;
14 }
15 int dis[maxn][maxn],x,y,n; bool bad[maxn][maxn]; queue<pair<int,int> >q;
16 int main(){
17     x=read()+500; y=read()+500; n=read(); inc(i,1,n){int x=read()+500,y=read()+500; bad[x][y]=1;}
18     q.push(make_pair(500,500)); memset(dis,-1,sizeof(dis)); dis[500][500]=0;
19     while(!q.empty()){
20         int xx=q.front().first,yy=q.front().second; q.pop();
21         if(xx>-1000&&!bad[xx-1][yy]&&dis[xx-1][yy]==-1){
22             q.push(make_pair(xx-1,yy)); dis[xx-1][yy]=dis[xx][yy]+1;
23             if(xx-1==x&&yy==y){printf("%d",dis[xx-1][yy]); break;}
24         }
25         if(xx<1000&&!bad[xx+1][yy]&&dis[xx+1][yy]==-1){
26             q.push(make_pair(xx+1,yy)); dis[xx+1][yy]=dis[xx][yy]+1;
27             if(xx+1==x&&yy==y){printf("%d",dis[xx+1][yy]); break;}
28         }
29         if(yy>-1000&&!bad[xx][yy-1]&&dis[xx][yy-1]==-1){
30             q.push(make_pair(xx,yy-1)); dis[xx][yy-1]=dis[xx][yy]+1;
31             if(xx==x&&yy-1==y){printf("%d",dis[xx][yy-1]); break;}
32         }
33         if(yy<1000&&!bad[xx][yy+1]&&dis[xx][yy+1]==-1){
34             q.push(make_pair(xx,yy+1)); dis[xx][yy+1]=dis[xx][yy]+1;
35             if(xx==x&&yy+1==y){printf("%d",dis[xx][yy+1]); break;}
36         }
37     }
38     return 0;
39 }