【wikioi1537】血色先锋队

#include<iostream>#include<cstdio>#include<cstring>#include<utility>#include<queue>using namespace std;int n,m,a,b,t=0,w=1,map[501][501];const int xi[4]={-1,0,1,0},yi[4]={0,-1,0,1};queue<pair<int,int> > q;void bfs(){while(!q.empty()){for(int i=0;i<=3;i++){int nowx=q.front().first+xi[i],nowy=q.front().second+yi[i],t=map[q.front().first][q.front().second];if(map[nowx][nowy]!=-1||nowx<1||nowy<1||nowx>n||nowy>m)continue;map[nowx][nowy]=t+1;q.push(make_pair(nowx,nowy));}q.pop();}}int main(){scanf("%d%d%d%d",&n,&m,&a,&b);memset(map,-1,sizeof(map));for(int i=1;i<=a;i++){int x,y;scanf("%d%d",&x,&y);map[x][y]=0;q.push(make_pair(x,y));}bfs();for(int i=1;i<=b;i++){int x,y;scanf("%d%d",&x,&y);printf("%d\n",map[x][y]);}return 0;}