用下map就行~~qwp~~
by huta0 @ 2023-11-04 17:41:23
@[WangYao0126](/user/815011)
```
#include<bits/stdc++.h>
using namespace std;
const int maxn=1e6+10;
int a[maxn],n;
int c;
int fnd_first(int x){
int l=0,r=n+1;
while(l+1<r){
int mid=(l+r)>>1;
if(a[mid]<=x) l=mid;
else r=mid;
}
return l;
}
int fnd_last(int x){
int l=0,r=n+1;
while(l+1<r){
int mid=(l+r)>>1;
if(a[mid]<x) l=mid;
else r=mid;
}
return l;
}
int main(){
ios::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
cin>>n>>c;
for(int i=1;i<=n;i++) cin>>a[i];
sort(a+1,a+n+1);
int ans=0;
for(int i=1;i<=n;i++){
ans+=fnd_first(a[i]+c)-fnd_last(a[i]+c);
}
cout<<ans<<endl;
return 0;
}
```
改了改二分和计算部分，看看行不行
by skyskyCCC @ 2023-11-04 17:58:14
@[skyskyCCC](/user/541739) 万分感谢！！！
by WangYao0126 @ 2023-11-04 18:14:00
@[WangYao0126](/user/815011) 不客气
by skyskyCCC @ 2023-11-04 18:16:56
@[WangYao0126](/user/815011) 注意ans要开long long否则第三个点会错
by skyskyCCC @ 2023-11-04 18:31:35
@[WangYao0126](/user/815011) 其实您原先的代码中的二分中的判断中大于小于号写反了
by skyskyCCC @ 2023-11-04 18:41:30
@[WangYao0126](/user/815011)
这份就只改了改二分，应该仍然可以过
```
#include<bits/stdc++.h>
using namespace std;
const int maxn=1e6+10;
int a[maxn],n;
int c;
int fnd_first(int x){
int l=1,r=n;
while(l<r){
int mid=(l+r)/2;
if(a[mid]>=x) r=mid;
else l=mid+1;
}
return r;
}
int fnd_last(int x){
int l=1,r=n;
while(l<=r){
int mid=(l+r)/2;
if(a[mid]<=x) l=mid+1;
else r=mid-1;
}
return r;
}
int main(){
ios::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
cin>>n>>c;
for(int i=1;i<=n;i++) cin>>a[i];
sort(a+1,a+n+1);
long long ans=0;
for(int i=1;i<=n;i++){
int A=a[i];
int l=fnd_first(A-c);
int r=fnd_last(A-c);
if(a[l]==A-c) ans+=(r-l+1);
}
cout<<ans<<endl;
return 0;
}
```
by skyskyCCC @ 2023-11-04 18:43:52