啊，这代码现在不会TLE了，不过全WA
by ChthollyMeow @ 2020-05-26 22:38:00
@[_珂朵莉](/user/332022)
1.$cmp$ 写错了，应该是 $a_p>a_q$ 而且数据已加强需要判重，所以这样
```cpp
bool cmp(int p,int q){
if(a[p]==a[q]) return p>q;
return a[p]>a[q];
}
```
2.数据加强，要开 $long\ long$
by Acestar @ 2020-05-26 23:14:51
```cpp
#include<bits/stdc++.h>
#define RE register
#define int long long
using namespace std;
int a[500005],b[500005],c[500005],n,anss=0;
inline void modify(RE int x){
for(RE int i=x;i<=n;i+=(i&(-i))){
c[i]++;
}
}
inline int find(RE int x){
RE int ans=0;
for(RE int i=x;i;i-=(i&(-i))){
ans+=c[i];
}
return ans;
}
bool cmp(int p,int q){
if(a[p]==a[q]) return p>q;
return a[p]>a[q];
}
inline int read(){
char ch=getchar();
int x=0,f=1;
while(ch<'0'||ch>'9'){if(ch=='-') f=-1;ch=getchar();}
while(ch>='0'&&ch<='9') x=x*10+ch-48,ch=getchar();
return x*f;
}
signed main(){
n=read();
for(RE int i=1;i<=n;i++){
a[i]=read();
b[i]=i;//离散化
}
sort(b+1,b+n+1,cmp);
for(RE int i=1;i<=n;i++){
modify(b[i]);
anss+=find(b[i]-1);
}
printf("%lld",anss);
return 0;
}
```
by Acestar @ 2020-05-26 23:15:13