洛谷P1789【Mc生存】插火把 题解

#include<bits/stdc++.h>
//Minecraft 666
using namespace std;
int a[110][110];
int n,m,k,ans;
int main(){
    scanf("%d%d%d",&n,&m,&k);
    for(int i=1;i<=m;i++){
        int x,y;
        scanf("%d%d",&x,&y);
        a[x-2][y]=1;a[x-1][y]=1;a[x][y]=1;a[x+1][y]=1;a[x-1][y-1]=1;a[x+1][y-1]=1;
        a[x+2][y]=1;a[x][y+2]=1;a[x][y+1]=1;a[x][y-1]=1;a[x][y-2]=1;a[x+1][y+1]=1;a[x-1][y+1]=1;
    }
    for(int i=1;i<=k;i++){
        int x,y;
        scanf("%d%d",&x,&y);
        a[x-2][y-2]=1;a[x-1][y-2]=1;a[x][y-2]=1;a[x+1][y-2]=1;a[x+2][y-2]=1;
        a[x-2][y-1]=1;a[x-1][y-1]=1;a[x][y-1]=1;a[x+1][y-1]=1;a[x+2][y-1]=1;
        a[x-2][y]=1;a[x-1][y]=1;a[x][y]=1;a[x+1][y]=1;a[x+2][y]=1;
        a[x-2][y+1]=1;a[x-1][y+1]=1;a[x][y+1]=1;a[x+1][y+1]=1;a[x+2][y+1]=1;
        a[x-2][y+2]=1;a[x-1][y+2]=1;a[x][y+2]=1;a[x+1][y+2]=1;a[x+2][y+2]=1;
    }
    for(int i=1;i<=n;i++)
        for(int j=1;j<=n;j++)
            if(a[i][j]==0) ans++;
    printf("%d\n",ans);
    return 0;
}