Submission #1365265

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Source Code Expand

#include <bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
struct __test {} test;
using namespace std;
template <typename T>const __test &operator<<(const __test& d,
const T& v) {return cerr << "\033[31m" << v << "\033[0m",d;}
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef long long ll;

const int N = 1e5+5;
int A[N],B[N],n;
map<int,int> loc;

int main() {
	ios::sync_with_stdio(0); cin.tie(0);
	cin >> n;
	for(int i = 0; i < n; ++i) {
		cin >> A[i];
		B[i] = A[i];
	}
	sort(B,B+n);
	for(int i = 0; i < n; ++i)
		loc[B[i]] = i;
	int ans = 0;
	for(int i = 0; i < n; ++i) {
		ans += loc[A[i]]%2 != i%2;
	}
	cout << ans/2 << "\n";
}

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