Submission #1444036

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Source Code Expand

#include<iostream>
#include<algorithm>
#include<vector>
#include<complex>
using namespace std;
int n,a[100010];
vector<int> v,p;
int main(){
	cin>>n;
	for(int i=0;i<n;i++){
		cin>>a[i];a[i]=-a[i];
		if(i%2==1)v.push_back(a[i]);
		else p.push_back(a[i]);
	}
	sort(a,a+n);
	sort(v.begin(),v.end());
	sort(p.begin(),p.end());
	long long ans=0;
	for(int i=0;i<v.size();i++){
		int k=lower_bound(a,a+n,v[i])-a;
		ans+=abs(i*2+1-k);
	}
	for(int i=0;i<p.size();i++){
		int k=lower_bound(a,a+n,p[i])-a;
		ans+=abs(i*2-k);
	}
	cout<<ans/2<<endl;
	return 0;
}

Submission Info

Judge Result