OIer们**血泪**的教训
by Laoshan_PLUS @ 2023-06-08 20:17:25
@[Laoshan_PLUS](/user/498837) 6
by No0Chenquanlin @ 2023-06-09 21:14:10
@[No0Chenquanlin](/user/751575)
为什么这个开了`#define int long long`也WA
```
#include<iostream>
#include<cstdio>
#define int long long
using namespace std;
int f[1010][1010],bx,by,mx,my;
int a[1010][1010];
signed main(){
int x=0,y=0;
cin>>bx>>by>>mx>>my;
a[my+1][mx+2]=1;
a[my+2][mx+1]=1;
a[my+2][mx-1]=1;
a[my+1][mx-2]=1;
a[my-1][mx-2]=1;
a[my-2][mx-1]=1;
a[my-2][mx+1]=1;
a[my-1][mx+2]=1;
a[my][mx]=1;
f[0][0]=1;
for(y=0;y<=by;y++){
for(x=0;x<=bx;x++){
if(y==0&&x==0||a[y][x]){
continue;
}
else if(y==0){
f[y][x]=f[y][x-1];
}else if(x==0){
f[y][x]=f[y-1][x];
}else{
f[y][x]=f[y-1][x]+f[y][x-1];
}
}
}
cout<<f[by][bx];
return 0;
}
```
by xueruo @ 2023-06-10 13:43:32
打错了，是RE
by xueruo @ 2023-06-10 13:43:50
@[xueruo](/user/638718)
没有判断是否访问了无效内存。
建议全体下标+2
by No0Chenquanlin @ 2023-06-10 18:56:03
orz
by chuxm @ 2023-06-15 21:00:09