CodeForces 598D Igor In the Museum

#include<iostream>
#include<cstring>
#include<cmath>
#include<queue>
#include<algorithm>
#include<cstdio>
using namespace std;

const int maxn=1000+10;
char s[maxn][maxn];
struct X
{
int x,y;
X(int a,int b)
{
x=a;
y=b;
}
};
queue<X>Q;
int n,m,k;
bool flag[maxn][maxn];
int ans[maxn][maxn];
int dir[4][2]={
{1,0},
{-1,0},
{0,-1},
{0,1}
};

bool P(int a,int b)
{
if(a>=0&&a<n&&b>=0&&b<m&&s[a][b]=='.') return 1;
return 0;
}

int tot;

int check(int a,int b)
{
int res=0;

if(a-1>=0&&a-1<n&&b>=0&&b<m&&s[a-1][b]=='*') res++;
if(a+1>=0&&a+1<n&&b>=0&&b<m&&s[a+1][b]=='*') res++;
if(a>=0&&a<n&&b-1>=0&&b-1<m&&s[a][b-1]=='*') res++;
if(a>=0&&a<n&&b+1>=0&&b+1<m&&s[a][b+1]=='*') res++;

return res;
}

void dfs(int a,int b)
{
flag[a][b]=1;

Q.push(X(a,b));

tot=tot+check(a,b);

for(int i=0;i<4;i++)
{
int ta=a+dir[i][0];
int tb=b+dir[i][1];
if(P(ta,tb)==0) continue;
if(flag[ta][tb]==1) continue;
dfs(ta,tb);
}
}

int main()
{
scanf("%d%d%d",&n,&m,&k);
for(int i=0;i<n;i++) scanf("%s",s[i]);

memset(flag,0,sizeof flag);
memset(ans,0,sizeof ans);

for(int i=0;i<n;i++)
{
for(int j=0;j<m;j++)
{
if(s[i][j]=='*') continue;
tot=0;
if(flag[i][j]==1) continue;

dfs(i,j);
while(!Q.empty()){
ans[Q.front().x][Q.front().y]=tot;
Q.pop();
}
}
}

for(int i=1;i<=k;i++)
{
int tx,ty; scanf("%d%d",&tx,&ty);
printf("%d\n",ans[tx-1][ty-1]);
}

return 0;
}