Submission #1595309

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Source Code Expand

#include <bits/stdc++.h>
#define REP(i,n) for(int i=0;i<(int)(n);i++)
#define ALL(x) (x).begin(),(x).end()
#define LL long long

using namespace std;

int main(){

    int N;cin>>N;
    vector<int> odd;
    vector<int> even;

    REP(i,N){
        int a;cin>>a;
        if((i+1)%2)odd.push_back(a);
        else even.push_back(a);
    }
    sort(ALL(odd));
    sort(ALL(even));

    int ans=0;
    REP(i,odd.size())ans  += upper_bound(even.begin()+i,even.end(),odd[i])-(even.begin()+i);
    REP(i,even.size())ans += upper_bound(odd.begin()+1+i,odd.end(),even[i])-(odd.begin()+1+i);
    cout<<ans<<endl;

    return 0;
}

Submission Info

Judge Result