正题

题目链接:https://www.luogu.org/problemnew/show/P1332

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题目大意

对于每个领主求与最近的感染源的距离

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解题思路

那么水还要我讲？？？

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$code$

#include<cstdio>
#include<algorithm>
#include<queue>
using namespace std;
const int N=510;
int v[N][N],n,m,a,b;
queue<int> qx,qy;
const int dx[4]={0,0,1,-1},dy[4]={1,-1,0,0};
void bfs()
{while(!qx.empty()){int x=qx.front(),y=qy.front();qx.pop();qy.pop();for(int k=0;k<4;k++){int zx=x+dx[k],zy=y+dy[k];if(x<=0||y<=0||x>n||y>m||v[zx][zy]) continue;v[zx][zy]=v[x][y]+1;qx.push(zx);qy.push(zy);}}
}
int main()
{scanf("%d%d%d%d",&n,&m,&a,&b);for(int i=1;i<=a;i++){int x,y;scanf("%d%d",&x,&y);qx.push(x);qy.push(y);v[x][y]=1;}bfs();for(int i=1;i<=b;i++){int x,y; scanf("%d%d",&x,&y);printf("%d\n",v[x][y]-1);}
}