Submission #843074

#	Time	Username	Problem	Language	Result	Execution time	Memory
843074		fanwen	Abracadabra (CEOI22_abracadabra)	C++17	100 / 100	484 ms	47376 KiB

Main

#include <bits/stdc++.h>

using namespace std;

#define MASK(x) (1LL << (x))
#define BIT(x, i) (((x) >> (i)) & 1)
#define ALL(x) (x).begin(), (x).end()
#define REP(i, n) for (int i = 0, _n = n; i < _n; ++i)
#define FOR(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define FORD(i, a, b) for (int i = (a), _b = (b); i >= _b; --i)
#define FORE(i, a, b) for (int i = (a), _b = (b); i < _b; ++i)
#define debug(...) "[" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "
#define file(name) if (fopen(name".inp", "r")) { freopen(name".inp", "r", stdin); freopen(name".out", "w", stdout); }

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; }

template <class T> struct Fenwick_Tree {
    vector<T> bit;
    int n, LOG;
    Fenwick_Tree(int _n = 0) : n(_n), bit(_n + 5) {
        this->LOG = 32 - __builtin_clz(n);
    }

    void clear() { fill(bit.begin(), bit.end(), T(0)); }

    void update(int u, T val) {
        // cout << u << " " << val << '\n';
        for (; u <= n; u += u & -u) bit[u] += val;
    }

    T get(int u) {
        T ans = 0;
        assert(u <= n);
        for (; u; u -= u & -u) ans += bit[u];
        return ans;
    }

    T get(int l, int r) {
        return get(r) - get(l - 1);
    }

    int lower_bound(T x) {
        int pos = 0;
        for (int k = LOG - 1; k >= 0; --k) {
            if(pos + (1 << k) <= n && bit[pos + (1 << k)] < x) {
                pos ^= 1 << k;
                x -= bit[pos];
            }
        }
        return pos + 1;
    }
};

const int MAXN = 2e5 + 5;

int N, Q, a[MAXN], p[MAXN], ans[MAXN * 5], nxt[MAXN];
vector <pair <int, int>> queries[MAXN];

void you_make_it(void) {
    cin >> N >> Q;
    FOR(i, 1, N) cin >> a[i], p[a[i]] = i;
    FOR(i, 1, Q) {
        int t, x; cin >> t >> x;
        queries[min(t, N)].emplace_back(x, i);
    }
    stack <int> st;
    st.push(N + 1), a[N + 1] = N + 1;
    FORD(i, N, 1) {
        while(!st.empty() and a[st.top()] <= a[i]) st.pop();
        nxt[i] = st.top();
        st.push(i);
    }
    for (auto [x, i] : queries[0]) ans[i] = a[x];
    int lt = 1;
    Fenwick_Tree <int> bit(N);
    while(lt <= N / 2) {
        bit.update(a[lt], min(N / 2 + 1, nxt[lt]) - lt);
        lt = nxt[lt];
    }
    lt = N / 2 + 1;
    while(lt <= N) {
        bit.update(a[lt], min(N + 1, nxt[lt]) - lt);
        lt = nxt[lt];
    }
    // exit(0);
    FOR(q, 1, N) {
        for (auto [x, i] : queries[q]) {
            int id = bit.lower_bound(x);
            ans[i] = a[x - bit.get(id - 1) + p[id] - 1];
        }
        int id = bit.lower_bound(N / 2);
        if(bit.get(id) <= N / 2) continue;

        int lt = N / 2 - bit.get(id - 1) + p[id];
        int rt = bit.get(id, id) + p[id] - 1;
        bit.update(id, N / 2 - bit.get(id));
        while(lt <= rt) {
            bit.update(a[lt], min(rt + 1, nxt[lt]) - lt);
            lt = nxt[lt];
        }
    }
    FOR(i, 1, Q) cout << ans[i] << '\n';
}

signed main() {

#ifdef LOCAL
    freopen("TASK.inp", "r", stdin);
    freopen("TASK.out", "w", stdout);
#endif
    auto start_time = chrono::steady_clock::now();

    cin.tie(0), cout.tie(0) -> sync_with_stdio(0);

    you_make_it();

    auto end_time = chrono::steady_clock::now();

    cerr << "\nExecution time : " << chrono::duration_cast <chrono::milliseconds> (end_time - start_time).count() << "[ms]" << endl;

    return (0 ^ 0);
}

// Dream it. Wish it. Do it.

Compilation message (stderr)

Main.cpp: In instantiation of 'Fenwick_Tree<T>::Fenwick_Tree(int) [with T = int]':
Main.cpp:76:29:   required from here
Main.cpp:20:9: warning: 'Fenwick_Tree<int>::n' will be initialized after [-Wreorder]
   20 |     int n, LOG;
      |         ^
Main.cpp:19:15: warning:   'std::vector<int> Fenwick_Tree<int>::bit' [-Wreorder]
   19 |     vector<T> bit;
      |               ^~~
Main.cpp:21:5: warning:   when initialized here [-Wreorder]
   21 |     Fenwick_Tree(int _n = 0) : n(_n), bit(_n + 5) {
      |     ^~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 40 / 40
• Subtask 3: 25 / 25
• Subtask 4: 25 / 25