Language: C++

#include<iostream>
#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<algorithm>
#include<cmath>
#define eps 1e-20
using namespace std;
const double pi=3.14159265358979323846;
int cnt=0,n,get=0;
int xa,xb,ya,yb,xmi,xma,ymi,yma;
struct node{
	int x,y;
}p[200010];
int best[200010];
double ans;
bool cmp(node a,node b){
	return a.x<b.x;
}
int find(int x){
	int l=1,r=get+1,mid;
	while(l+1<r){
		mid=(l+r)>>1;
		if(best[mid]>=x)  l=mid+1;
		else  r=mid;
	}
	if(best[l]>=x)  return r;
	return l;
}
int check(int x){
	int l=1,r=get+1,mid;
	while(l+1<r){
		mid=(l+r)>>1;
		if(best[mid]<=x)  l=mid+1;
		else  r=mid;
	}
	if(best[l]<=x)  return r;
	return l;
}
int main(){
	scanf("%d%d%d%d",&xa,&ya,&xb,&yb);
	if(xa>xb){
		swap(xa,xb);swap(ya,yb);
	}
	xmi=xa;xma=xb-xmi;
	ymi=min(ya,yb);yma=max(ya,yb)-ymi;
	xa-=xmi;xb-=xmi;ya-=ymi;yb-=ymi;
	scanf("%d",&n);
	int i,j,a,b;
	for(i=1;i<=n;++i){
		scanf("%d%d",&a,&b);
		a-=xmi;b-=ymi;
		if(a<0 || b<0 || a>xma || b>yma)  continue ;
		p[++cnt].x=a;p[cnt].y=b;
	}
	if(cnt==0){
		ans=100.0*(xma+yma);printf("%.15lf\n",ans);return 0;
	}
	if(xa==xb && ya==yb){
		ans=0;printf("%.15lf\n",ans);return 0;
	}
	if(xa==xb){
		ans=100.0*yma;ans=ans-20.0*cnt;ans=ans+pi*10.0*cnt;
		printf("%.15lf\n",ans);return 0;
	}
	if(ya==yb){
		ans=100.0*xma;ans=ans-20.0*cnt;ans=ans+pi*10.0*cnt;
		printf("%.15lf\n",ans);return 0;
	}
	sort(p+1,p+1+cnt,cmp);
	if(ya>yb){
		memset(best,0,sizeof(best));
		get=1;
		for(i=1;i<=cnt;++i){
			int xx=find(p[i].y);
			best[xx]=p[i].y;
			if(xx>get)  get=xx;
		}
	}
	if(ya<yb){
		memset(best,0,sizeof(best));
		get=0;
		for(i=1;i<=cnt;++i){
			int xx=check(p[i].y);
			best[xx]=p[i].y;
			if(xx>get)  get=xx;
		}
	}
	ans=100.0*(xma+yma);
	ans-=20.0*get;
	ans+=pi*5.0*get;
	printf("%.15lf\n",ans);
	return 0;
}

Compiler output:
a.cc: In function 'int find(int)':
a.cc:21:19: error: reference to 'get' is ambiguous
   21 |         int l=1,r=get+1,mid;
      |                   ^~~
In file included from /usr/include/c++/14/bits/memory_resource.h:47,
                 from /usr/include/c++/14/string:68,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/tuple:2517:5: note: candidates are: 'template<class _Tp, class ... _Types> constexpr const _Tp&& std::get(const tuple<_Elements ...>&&)'
 2517 |     get(const tuple<_Types...>&& __t) noexcept
      |     ^~~
/usr/include/c++/14/tuple:2505:5: note:                 'template<class _Tp, class ... _Types> constexpr const _Tp& std::get(const tuple<_Elements ...>&)'
 2505 |     get(const tuple<_Types...>& __t) noexcept
      |     ^~~
/usr/include/c++/14/tuple:2494:5: note:                 'template<class _Tp, class ... _Types> constexpr _Tp&& std::get(tuple<_Elements ...>&&)'
 2494 |     get(tuple<_Types...>&& __t) noexcept
      |     ^~~
/usr/include/c++/14/tuple:2483:5: note:                 'template<class _Tp, class ... _Types> constexpr _Tp& std::get(tuple<_Elements ...>&)'
 2483 |     get(tuple<_Types...>& __t) noexcept
      |     ^~~
/usr/include/c++/14/tuple:2476:5: note:                 'template<long unsigned int __i, class ... _Elements> constexpr std::__enable_if_t<(__i >= sizeof... (_Types))> std::get(const tuple<_Elements ...>&)'
 2476 |     get(const tuple<_Elements...>&) = delete;
      |     ^~~
In file included from /usr/include/c++/14/bits/stl_algobase.h:64,
                 from /usr/include/c++/14/string:51:
/usr/include/c++/14/bits/stl_pair.h:1307:5: note:                 'template<class _Tp, class _Up> constexpr const _Tp&& std::get(const pair<_Up, _Tp>&&)'
 1307 |     get(const pair<_Up, _Tp>&& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1302:5: note:                 'template<class _Tp, class _Up> constexpr _Tp&& std::get(pair<_Up, _Tp>&&)'
 1302 |     get(pair<_Up, _Tp>&& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1297:5: note:                 'template<class _Tp, class _Up> constexpr const _Tp& std::get(const pair<_Up, _Tp>&)'
 1297 |     get(const pair<_Up, _Tp>& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1292:5: note:                 'template<class _Tp, class _Up> constexpr _Tp& std::get(pair<_Up, _Tp>&)'
 1292 |     get(pair<_Up, _Tp>& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1287:5: note:                 'template<class _Tp, class _Up> constexpr const _Tp&& std::get(const pair<_T1, _T2>&&)'
 1287 |     get(const pair<_Tp, _Up>&& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1282:5: note:                 'template<class _Tp, class _Up> constexpr _Tp&& std::get(pair<_T1, _T2>&&)'
 1282 |     get(pair<_Tp, _Up>&& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1277:5: note:                 'template<class _Tp, class _Up> constexpr const _Tp& std::get(const pair<_T1, _T2>&)'
 1277 |     get(const pair<_Tp, _Up>& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1272:5: note:                 'template<class _Tp, class _Up> constexpr _Tp& std::get(pair<_T1, _T2>&)'
 1272 |     get(pair<_Tp, _Up>& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:150:5: note:                 'template<long unsigned int _Int, class _Tp, long unsigned int _Nm> constexpr const _Tp&& std::get(const array<_Tp, _Nm>&&)'
  150 |     get(const array<_Tp, _Nm>&&) noexcept;
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:146:5: note:                 'template<long unsigned int _Int, class _Tp, long unsigned int _Nm> constexpr const _Tp& std::get(const array<_Tp, _Nm>&)'
  146 |     get(const array<_Tp, _Nm>&) noexcept;
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:142:5: note:                 'template<long unsigned int _Int, class _Tp, long unsigned int _Nm> constexpr _Tp&& std::get(array<_Tp, _Nm>&&)'
  142 |     get(array<_Tp, _Nm>&&) noexcept;
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:138:5: note:                 'template<long unsigned int _Int, class _Tp, long unsigned int _Nm> constexpr _Tp& std::get(array<_Tp, _Nm>&)'
  138 |     get(array<_Tp, _Nm>&) noexcept;
      |     ^~~
/usr/include/c++/14/tuple:2466:5: note:                 'template<long unsigned int __i, class ... _Elements> constexpr std::__tuple_element_t<__i, std::tuple<_Elements ...> >&& std::get(const tuple<_Elements ...>&&)'
 2466 |     get(const tuple<_Elements...>&& __t) noexcept
      |     ^~~
/usr/include/c++/14/tuple:2457:5: note:                 'template<long unsigned int __i, class ... _Elements> constexpr std::__tuple_element_t<__i, std::tuple<_Elements ...> >&& std::get(tuple<_Elements ...>&&)'
 2457 |     get(tuple<_Elements...>&& __t) noexcept
      |     ^~~
/usr/include/c++/14/tuple:2451:5: note:                 'template<long unsigned int __i, class ... _Elements> constexpr std::__tuple_element_t<__i, std::tuple<_Elements ...> >& std::get(const tuple<_Elements ...>&)'
 2451 |     get(const tuple<_Elements...>& __t) noexcept
      |     ^~~
/usr/include/c++/14/tuple:2445:5: note:                 'template<long unsigned int __i, class ... _Elements> constexpr std::__tuple_element_t<__i, std::tuple<_Elements ...> >& std::get(tuple<_Elements ...>&)'
 2445 |     get(tuple<_Elements...>& __t) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1265:5: note:                 'template<long unsigned int _Int, class _Tp1, class _Tp2> constexpr const typename std::tuple_element<_Int, std::pair<_Tp1, _Tp2> >::type&& std::get(const pair<_Tp1, _Tp2>&&)'
 1265 |     get(const pair<_Tp1, _Tp2>&& __in) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1260:5: note:                 'template<long unsigned int _Int, class _Tp1, class _Tp2> constexpr const typename std::tuple_element<_Int, std::pair<_Tp1, _Tp2> >::type& std::get(const pair<_Tp1, _Tp2>&)'
 1260 |     get(const pair<_Tp1, _Tp2>& __in) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1255:5: note:                 'template<long unsigned int _Int, class _Tp1, class _Tp2> constexpr typename std::tuple_element<_Int, std::pair<_Tp1, _Tp2> >::type&& std::get(pair<_Tp1, _Tp2>&&)'
 1255 |     get(pair<_Tp1, _Tp2>&& __in) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1250:5: note:                 'template<long unsigned int _Int, class _Tp1, class _Tp2> constexpr typename std::tuple_element<_Int, std::pair<_Tp1, _Tp2> >::type& std::get(pair<_Tp1, _Tp2>&)'
 1250 |     get(pair<_Tp1, _Tp2>& __in) noexcept
      |     ^~~
a.cc:10:13: note:                 'int get'
   10 | int cnt=0,n,get=0;
      |             ^~~
a.cc:23:17: error: 'mid' was not declared in this scope
   23 |                 mid=(l+r)>>1;
      |                 ^~~
a.cc: In function 'int check(int)':
a.cc:31:19: error: reference to 'get' is ambiguous
   31 |         int l=1,r=get+1,mid;
      |                   ^~~
/usr/include/c++/14/tuple:2517:5: note: candidates are: 'template<class _Tp, class ... _Types> constexpr const _Tp&& std::get(const tuple<_Elements ...>&&)'
 2517 |     get(const tuple<_Types...>&& __t) noexcept
      |     ^~~
/usr/include/c++/14/tuple:2505:5: note:                 'template<class _Tp, class ... _Types> constexpr const _Tp& std::get(const tuple<_Elements ...>&)'
 2505 |     get(const tuple<_Types...>& __t) noexcept
      |     ^~~
/usr/include/c++/14/tuple:2494:5: note:                 'template<class _Tp, class ... _Types> constexpr _Tp&& std::get(tuple<_Elements ...>&&)'
 2494 |     get(tuple<_Types...>&& __t) noexcept
      |     ^~~
/usr/include/c++/14/tuple:2483:5: note:                 'template<class _Tp, class ... _Types> constexpr _Tp& std::get(tuple<_Elements ...>&)'
 2483 |     get(tuple<_Types...>& __t) noexcept
      |     ^~~
/usr/include/c++/14/tuple:2476:5: note:                 'template<long unsigned int __i, class ... _Elements> constexpr std::__enable_if_t<(__i >= sizeof... (_Types))> std::get(const tuple<_Elements ...>&)'
 2476 |     get(const tuple<_Elements...>&) = delete;
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1307:5: note:                 'template<class _Tp, class _Up> constexpr const _Tp&& std::get(const pair<_Up, _Tp>&&)'
 1307 |     get(const pair<_Up, _Tp>&& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1302:5: note:                 'template<class _Tp, class _Up> constexpr _Tp&& std::get(pair<_Up, _Tp>&&)'
 1302 |     get(pair<_Up, _Tp>&& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1297:5: note:                 'template<class _Tp, class _Up> constexpr const _Tp& std::get(const pair<_Up, _Tp>&)'
 1297 |     get(const pair<_Up, _Tp>& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1292:5: note:                 'template<class _Tp, class _Up> constexpr _Tp& std::get(pair<_Up, _Tp>&)'
 1292 |     get(pair<_Up, _Tp>& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1287:5: note:                 'template<class _Tp, class _Up> constexpr const _Tp&& std::get(const pair<_T1, _T2>&&)'
 1287 |     get(const pair<_Tp, _Up>&& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1282:5: note:                 'template<class _Tp, class _Up> constexpr _Tp&& std::get(pair<_T1, _T2>&&)'
 1282 |     get(pair<_Tp, _Up>&& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1277:5: note:                 'template<class _Tp, class _Up> constexpr const _Tp& std::get(const pair<_T1, _T2>&)'
 1277 |     get(const pair<_Tp, _Up>& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:1272:5: note:                 'template<class _Tp, class _Up> constexpr _Tp& std::get(pair<_T1, _T2>&)'
 1272 |     get(pair<_Tp, _Up>& __p) noexcept
      |     ^~~
/usr/include/c++/14/bits/stl_pair.h:150:5: note:                 'template<long unsigned int _Int, class _Tp, long unsigned i