Submission #1380762

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Source Code Expand

#include <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()
#define fi first
#define se second

template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }

typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, pll> P;
const ll INF = 1ll<<30;
const ll MOD = 1000000007;
const double EPS  = 1e-10;

template<typename T> struct BIT {
	vector<T> bit;
	int n;
	
	BIT() {}
	BIT(int n) : bit(vector<T>(n + 2, 0)), n(n) {}
	
	T sum(int i) {
		i++;
		T s = 0;
		while (i > 0) {
			s += bit[i];
			i -= i & -i;
		}
		return s;
	}
	
	void add(int i, T x) {
		i++;
		while (i <= n) {
			bit[i] += x;
			i += i & -i;
		}
	}
	
	T pquery(int i) {
		return sum(i) - sum(i - 1);
	}
	
	int lower_bound(T x) {
		int l = -1, r = bit.size();
		while (r - l > 1) {
			int m = (l + r) / 2;
			
			if (sum(m) >= x) r = m;
			else l = m;
		}
		if (r == bit.size()) r = -1;
		
		return r;
	}
};

int N;
int a[112345], pos[112345];

int main() {
	cin >> N;
	REP(i, N) scanf("%d", a + i);
	
	vector<int> cx;
	REP(i, N) cx.push_back(a[i]);
	sort(ALL(cx));
	REP(i, N) a[i] = lower_bound(ALL(cx), a[i]) - cx.begin();
	
	vector<int> v[2];
	REP(i, N) {
		if (i & 1) v[1].push_back(a[i]);
		else v[0].push_back(a[i]);
	}
	REP(i, 2) sort(ALL(v[i]));
	
	
	if (N >= 2 && v[1][0] == 0) swap(v[0], v[1]);
	vector<int> u;
	REP(i, N / 2) {
		u.push_back(v[0][i]);
		u.push_back(v[1][i]);
	}
	if (N & 1) u.push_back(v[0].back());
	
	BIT<int> bit(112345);
	REP(i, u.size()) {
		pos[u[i]] = i;
		bit.add(i, 1);
	}
	
	int ans = 0;
	REP(i, N) {
		bit.add(pos[i], -1);
		if (bit.sum(pos[i]) > 0) ans++;
	}
	
	
	cout << ans << endl;
	
	return 0;
}

Submission Info

Compile Error

./Main.cpp: In function ‘int main()’:
./Main.cpp:70:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result]
  REP(i, N) scanf("%d", a + i);
                              ^

Judge Result