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  1. #include<iostream>
  2. #include<algorithm>
  3. #include<vector>
  4. #include<cmath>
  5. #define pb push_back
  6. #define N 100000
  7. #define ll long long
  8. using namespace std;
  9.  
  10. vector<pair<ll,ll> > v;
  11. bool par=false;
  12.  
  13. bool checkpar(ll a,ll b){
  14. 	return (a&1 && b&1);
  15. }
  16.  
  17. ll solve(int n){
  18. 	ll ar=0,s1,s2,s3,m=0,m2,imax,vmax;
  19. 	s1=0;
  20. 	s2=v[n-1].second;imax=n-1;
  21. 	for(int i=n-2;i>=0;i--){
  22. 		s3=v[i].second;
  23. 		if(s3<=s2){
  24. 			if(s3<=s1)continue;
  25. 			s1=s3;
  26. 			ar=v[i].first*s1;
  27. 			m=ar>m?ar:m;
  28. 		}
  29. 		else{ 
  30. 		 	s2=s3;
  31. 		 	vmax=v[imax].second;
  32. 		 	if(s2>>1 >= vmax)
  33. 		 		{
  34. 		 			ar=(s2*v[i].first)>>1;
  35. 		 			m=ar>=m?ar:m;
  36. 		 			par=checkpar(s2,v[i].first);
  37. 		 		}
  38. 		 	else{
  39. 		 		ar=vmax*v[i].first;
  40. 		 		if(ar>m){m=ar;par=false;}
  41. 		 	}
  42.  
  43. 		 	imax=i;
  44. 		}
  45.  
  46. 	}
  47.  
  48. 	return m;
  49. }
  50.  
  51. int main()
  52. {
  53. 	int n,k=0;
  54. 	ll l,w,max=0,m2;
  55.  
  56. 	cin >> n;
  57. 	for(int i=0;i<n;i++){
  58. 		cin>>l>>w;
  59. 		 if(l<=w) v.pb(make_pair(l,w));
  60. 		 else v.pb(make_pair(w,l));
  61. 	}
  62. 	sort(v.begin(),v.end());
  63. 	max=solve(n);
  64. 	m2=(v[n-1].first*v[n-1].second)>>1;
  65. 	if(m2>=max){par=checkpar(v[n-1].first,v[n-1].second);max=m2;}
  66.  
  67. 	if(par)
  68. 		cout<<max<<".5";
  69. 	else
  70. 		cout<<max<<".0";
  71.  
  72. 	return 0;
  73. }
Success #stdin #stdout 0s 4356KB
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2.0
https://ideone.com/YzOuyB
language:
C++14 (gcc 8.3)
created:
4 years ago
visibility:
public

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