WA in #4 , i do not know the cause.
#include <iostream>
#include <algorithm>
#include <cmath>
#define ford(i,n) for (long i=1; i<=n; i++)
#define openfile freopen("1306.in4","r",stdin);
#define closefile freopen("out1.txt","w",stdout);
using namespace std;
const long maxn=130000;
long long n,a[maxn],x;
long long m,l;
void xuly1()
{
ford(i,n/2+1)
{
cin >> a[i];
push_heap(&a[1],&a[i+1]);
}
for(int i=n/2+2; i<=n ; i++)
{
cin >> x;
if (x==a[1])
{
a[n/2+1]=a[1];
push_heap(&a[1],&a[n/2+2]);
}
else
if (x<a[1])
{
pop_heap(&a[1],&a[n/2+2]);
a[n/2+1]=x;
push_heap(&a[1],&a[n/2+2]);
}
}
x=a[1]; pop_heap(&a[1],&a[n/2+2]);
m=x; l=a[1];
cout << (m+l)/2 ; m=(m+l) % 2 ;
if (m==1) cout << ".5" << "\n"; else cout << ".0" << "\n";
}
void xuly2()
{
ford(i,(n+1)/2)
{
cin >>a[i];
push_heap(&a[1],&a[i+1]);
}
for(int i=(n+1)/2+1; i<=n ; i++)
{
cin >> x;
if (x<a[1])
{
pop_heap(&a[1],&a[(n+1)/2+1]);
a[(n+1)/2]=x;
push_heap(&a[1],&a[(n+1)/2+1]);
}
}
cout << a[1] <<".0"<< endl;
}
int main()
{
// openfile; closefile;
cin >> n;
if (n % 2==0) xuly1() ; else xuly2();
cin >> n;
return 0;
}
