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@[editcom2000](/user/84379)
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判断越界，附上我的代码：
```cpp
#include <bits/stdc++.h>
using namespace std;
struct bit{
int x;
int y;
};
bool check(int x,int y,int n){
if(x<0 || x>=n || y<0 || y>=n)return false;
return true;
}
int main(){
int n,m,k;cin>>n>>m>>k;bool map[n][n];memset(map,1,sizeof(map));
bit hb[m],ys[k];for(int i=0;i<m;i++)cin>>hb[i].x>>hb[i].y;for(int i=0;i<k;i++)cin>>ys[i].x>>ys[i].y;
for(int i=0;i<m;i++){
if(check(--hb[i].x-2,--hb[i].y,n))map[hb[i].x-2][hb[i].y]=false;
if(check(hb[i].x-1,hb[i].y-1,n))map[hb[i].x-1][hb[i].y-1]=false;
if(check(hb[i].x-1,hb[i].y,n))map[hb[i].x-1][hb[i].y]=false;
if(check(hb[i].x-1,hb[i].y+1,n))map[hb[i].x-1][hb[i].y+1]=false;
if(check(hb[i].x,hb[i].y-2,n))map[hb[i].x][hb[i].y-2]=false;
if(check(hb[i].x,hb[i].y-1,n))map[hb[i].x][hb[i].y-1]=false;
if(check(hb[i].x,hb[i].y,n))map[hb[i].x][hb[i].y]=false;
if(check(hb[i].x,hb[i].y+1,n))map[hb[i].x][hb[i].y+1]=false;
if(check(hb[i].x,hb[i].y+2,n))map[hb[i].x][hb[i].y+2]=false;
if(check(hb[i].x+1,hb[i].y-1,n))map[hb[i].x+1][hb[i].y-1]=false;
if(check(hb[i].x+1,hb[i].y,n))map[hb[i].x+1][hb[i].y]=false;
if(check(hb[i].x+1,hb[i].y+1,n))map[hb[i].x+1][hb[i].y+1]=false;
if(check(hb[i].x+2,hb[i].y,n))map[hb[i].x+2][hb[i].y]=false;
}
for(int i=0;i<k;i++){
ys[i].x--;ys[i].y--;
for(int j=-2;j<=2;j++)for(int l=-2;l<=2;l++)if(check(ys[i].x+j,ys[i].y+l,n))map[ys[i].x+j][ys[i].y+l]=false;
}
int sum=0;for(int i=0;i<n;i++)for(int j=0;j<n;j++)if(map[i][j])sum++;
cout<<sum;
return 0;
}
```
by ihesro @ 2020-06-27 23:16:04