@[venti520](/user/780145) [在这问](https://www.luogu.com.cn/discuss?forum=P1102)
by clx201022 @ 2024-03-28 00:00:45
@[venti520](/user/780145) 排序用 `sort`，比你的那个快一点
by clx201022 @ 2024-03-28 00:03:44
@[venti520](/user/780145)
```cpp
#include<algorithm>
#include<cstdio>
using namespace std;
using ll=long long;
const int MAXN=2e5;
ll a[MAXN+1],n,c,ans;
int main()
{
scanf("%lld%lld",&n,&c);
for(int i=1;i<=n;i++)scanf("%lld",a+i/*等价于 &a[i]*/);
sort(a+1,a+n+1);
for(ll d=1,r=1,l=1;d<=n;d++)
{
while(r+1<=n&&a[r+1]-a[d]<=c)r++;//相同区间的右边
while(l<=n&&a[l]-a[d]<c)l++;//相同区间的左边
if(a[l]-a[d]==c&&a[r]-a[d]==c)ans+=r-l+1;
}
printf("%lld",ans);
return 0;
}
```
by clx201022 @ 2024-03-28 00:18:55
@[venti520](/user/780145) 下次别在这问，去[题目讨论版](https://www.luogu.com.cn/discuss?forum=problem)问
by clx201022 @ 2024-03-28 00:20:11