@[cuphead_P](/user/731197)
```cpp
#include <bits/stdc++.h>
#define int long long
using namespace std;
int a[200001];
map<int,int> m;
int main()
{
int n;
int c;
int ans=0;
cin>>n>>c;
for(int i=1;i<=n;i++)
{
cin>>a[i];
m[a[i]]++;
a[i]-=c;
}
for(int i=1;i<=n;i++)ans+=m[a[i]];
cout<<ans;
return 0;
}
```
要用map存,并把a-b=c变成a-c=b的问题
by zyhe2013 @ 2024-03-13 19:44:30
UID记得发我
by zyhe2013 @ 2024-03-13 19:44:53
@[zyhe2013](/user/905073) 282502268
by cuphead_P @ 2024-03-15 22:38:46