Submission #795827

#	Time	Username	Problem	Language	Result	Execution time	Memory
795827		marvinthang	Line Town (CCO23_day1problem3)	C++17	25 / 25	368 ms	25976 KiB

Main

/*************************************
*    author: marvinthang             *
*    created: 27.07.2023 20:51:29    *
*************************************/

#include <bits/stdc++.h>

using namespace std;

#define                  fi  first
#define                  se  second
#define                left  ___left
#define               right  ___right
#define                TIME  (1.0 * clock() / CLOCKS_PER_SEC)
#define             MASK(i)  (1LL << (i))
#define           BIT(x, i)  ((x) >> (i) & 1)
#define  __builtin_popcount  __builtin_popcountll
#define              ALL(v)  (v).begin(), (v).end()
#define           REP(i, n)  for (int i = 0, _n = (n); i < _n; ++i)
#define          REPD(i, n)  for (int i = (n); i-- > 0; )
#define        FOR(i, a, b)  for (int i = (a), _b = (b); i < _b; ++i) 
#define       FORD(i, b, a)  for (int i = (b), _a = (a); --i >= _a; ) 
#define       FORE(i, a, b)  for (int i = (a), _b = (b); i <= _b; ++i) 
#define      FORDE(i, b, a)  for (int i = (b), _a = (a); i >= _a; --i) 
#define        scan_op(...)  istream & operator >> (istream &in, __VA_ARGS__ &u)
#define       print_op(...)  ostream & operator << (ostream &out, const __VA_ARGS__ &u)
#ifdef LOCAL
    #include "debug.h"
#else
    #define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
    #define DB(...) 23
    #define db(...) 23
    #define debug(...) 23
#endif

template <class U, class V> scan_op(pair <U, V>)  { return in >> u.first >> u.second; }
template <class T> scan_op(vector <T>)  { for (size_t i = 0; i < u.size(); ++i) in >> u[i]; return in; }
template <class U, class V> print_op(pair <U, V>)  { return out << '(' << u.first << ", " << u.second << ')'; }
template <size_t i, class T> ostream & print_tuple_utils(ostream &out, const T &tup) { if constexpr(i == tuple_size<T>::value) return out << ")";  else return print_tuple_utils<i + 1, T>(out << (i ? ", " : "(") << get<i>(tup), tup); }
template <class ...U> print_op(tuple<U...>) { return print_tuple_utils<0, tuple<U...>>(out, u); }
template <class Con, class = decltype(begin(declval<Con>()))> typename enable_if <!is_same<Con, string>::value, ostream&>::type operator << (ostream &out, const Con &con) { out << '{'; for (__typeof(con.begin()) it = con.begin(); it != con.end(); ++it) out << (it == con.begin() ? "" : ", ") << *it; return out << '}'; }
template <class A, class B> bool minimize(A &a, B b)  { if (a > b) { a = b; return true; } return false; }
template <class A, class B> bool maximize(A &a, B b)  { if (a < b) { a = b; return true; } return false; }

// index from 0
template <class T = int>
    struct Fenwick {

        T *bit = nullptr;
        int n;

        Fenwick(int _n = 0) {
            resize(_n);
        }

        void reset(void) {
            fill(bit, bit + 1 + n, T(0));
        }

        void resize(int _n) {
            if (bit != nullptr) delete[] bit;
            n = _n;
            bit = new T[n + 1];
            reset();
        }

        void update(int i, T val) {
            assert(0 <= i);
            ++i;
            for (; i <= n; i += i & -i) bit[i] += val;
        }

        T get(int i) {
            if (i < 0) return T(0);
            ++i;
            i = min(i, n);
            T res(0);
            for (; i > 0; i -= i & -i)
                res += bit[i];
            return res;
        }

        int upper_bound(T val) {
            int res = 0;
            for (int i = __lg(n); i >= 0; --i) {
                if ((res | MASK(i)) <= n && val >= bit[res | MASK(i)]) {
                    res |= MASK(i);
                    val -= bit[res];
                }
            }
            return res;
        }

        int lower_bound(T val) {
            int res = 0;
            for (int i = __lg(n); i >= 0; --i) {
                if ((res | MASK(i)) <= n && val > bit[res | MASK(i)]) {
                    res |= MASK(i);
                    val -= bit[res];
                }
            }
            return res;
        }

    };

// end of template

const int MAX = 5e5 + 5;
const long long INF = 1e18;

int N, H[MAX], P[MAX];

void init(void) {
	cin >> N;
	REP(i, N) cin >> H[i];
}

void process(void) {
	for (int i = 0; i < N; i += 2) H[i] = -H[i];
	vector <int> order(N);
	iota(ALL(order), 0);
	sort(ALL(order), [&] (int a, int b) { return make_pair(abs(H[a]), -a) > make_pair(abs(H[b]), -b); });

	Fenwick <int> bit_pref(N), bit_suff(N), cnt_zero(N);
	REP(i, N) cnt_zero.update(i, 1);
	long long dp[2] = {0, INF};

	REP(l, N) {
		if (!H[order[l]]) break;
		int r = l;
		while (r + 1 < N && abs(H[order[r + 1]]) == abs(H[order[l]])) ++r;
		vector <tuple <int, long long, long long>> pos[2];
		FORE(i, l, r) {
			cnt_zero.update(order[i], -1);
			int pref_zero = cnt_zero.get(order[i]);
			int suff_zero = N - r - 1 - pref_zero;
			if (H[order[i]] < 0) pos[0].emplace_back(order[i], pref_zero, suff_zero);
			else pos[1].emplace_back(order[i], pref_zero, suff_zero);
		}

		REP(i, 2) {
			REP(j, (int) pos[i].size() - 1) get<1>(pos[i][j + 1]) += get<1>(pos[i][j]);
			REPD(j, (int) pos[i].size() - 1) get<2>(pos[i][j]) += get<2>(pos[i][j + 1]);
		
		}
		int sz = pos[0].size() + pos[1].size();
		long long nxt[2] = {INF, INF};
		REP(p, 2) {
			int pl = !p;
			int pr = !((N - l + p) & 1);
			vector <int> pref(sz, 0), suff(sz, 0);
			REP(i, sz) {
				int v = pl ^ (i & 1);
				if (i / 2 < pos[v].size()) pref[i] = get<0>(pos[v][i / 2]);
				v = pr ^ (i & 1);
				if (i / 2 < pos[v].size()) suff[sz - i - 1] = get<0>(pos[v][(int) pos[v].size() - i / 2 - 1]);
			}

			long long inv = 0;
			REPD(i, sz) {
				inv += bit_suff.get(suff[i] - 1);
				bit_suff.update(suff[i], 1);
			}

			REP(i, sz + 1) {
				int pos_pref[2], pos_suff[2];
				pos_pref[pl] = (i + 1) / 2;
				pos_pref[!pl] = i / 2;
				pos_suff[pr] = (int) pos[pr].size() - (sz - i + 1) / 2;
				pos_suff[!pr] = (int) pos[!pr].size() - (sz - i) / 2;

				if (pos_pref[0] == pos_suff[0] && pos_pref[1] == pos_suff[1]) {
					long long cur = inv;
					REP(i, 2) {
						if (pos_pref[i]) cur += get<1>(pos[i][pos_pref[i] - 1]);
						if (pos_suff[i] < pos[i].size()) cur += get<2>(pos[i][pos_suff[i]]);
					}
					minimize(nxt[p ^ (i & 1)], dp[p] + cur);
				}

				if (i < sz) {
					inv -= bit_suff.get(suff[i] - 1);
					inv -= bit_pref.get(N - suff[i] - 2);
					bit_suff.update(suff[i], -1);

					inv += bit_suff.get(pref[i] - 1);
					inv += bit_pref.get(N - pref[i] - 2);
					bit_pref.update(N - pref[i] - 1, +1);
				}
			}
			for (int i: pref) bit_pref.update(N - i - 1, -1);
		}
		dp[0] = nxt[0], dp[1] = nxt[1];
		l = r;
	}
	long long res = min(dp[0], dp[1]);
	cout << (res == INF ? -1 : res) << '\n';
}

int main(void) {
	ios_base::sync_with_stdio(false); cin.tie(nullptr); // cout.tie(nullptr);
	file("cco23p3");
	init();
	process();
	cerr << "Time elapsed: " << TIME << " s.\n";
	return (0^0);
}

Compilation message (stderr)

Main.cpp: In function 'void process()':
Main.cpp:155:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::tuple<int, long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  155 |     if (i / 2 < pos[v].size()) pref[i] = get<0>(pos[v][i / 2]);
      |         ~~~~~~^~~~~~~~~~~~~~~
Main.cpp:157:15: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::tuple<int, long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  157 |     if (i / 2 < pos[v].size()) suff[sz - i - 1] = get<0>(pos[v][(int) pos[v].size() - i / 2 - 1]);
      |         ~~~~~~^~~~~~~~~~~~~~~
Main.cpp:177:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::tuple<int, long long int, long long int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  177 |       if (pos_suff[i] < pos[i].size()) cur += get<2>(pos[i][pos_suff[i]]);
      |           ~~~~~~~~~~~~^~~~~~~~~~~~~~~
Main.cpp: In function 'int main()':
Main.cpp:30:61: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   30 |     #define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
      |                                                      ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:203:2: note: in expansion of macro 'file'
  203 |  file("cco23p3");
      |  ^~~~
Main.cpp:30:94: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   30 |     #define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }
      |                                                                                       ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
Main.cpp:203:2: note: in expansion of macro 'file'
  203 |  file("cco23p3");
      |  ^~~~

• Subtask 1: 3 / 3
• Subtask 2: 3 / 3
• Subtask 3: 3 / 3
• Subtask 4: 4 / 4
• Subtask 5: 4 / 4
• Subtask 6: 3 / 3
• Subtask 7: 2 / 2
• Subtask 8: 3 / 3