Submission #633225

#	Time	Username	Problem	Language	Result	Execution time	Memory
633225		Gromp15	Abracadabra (CEOI22_abracadabra)	C++17	100 / 100	530 ms	40216 KiB

Main

#include <bits/stdc++.h>
#define ll long long
#define ar array
using namespace std;
struct fenwick {
    int n, lg; vector<int> bit;
    fenwick(int a) : n(a), lg(__lg(n)), bit(a+1) {}
    int pref(int pos) {
        pos++;
        int ret = 0;
        if (pos > n) pos = n;
        while (pos) {
            ret += bit[pos], pos -= pos&-pos;
        }
        return ret;
    }
    int point(int pos) {
        return pref(pos) - pref(pos-1);
    }
    void update(int pos, int x) {
        pos++;
        while (pos <= n) {
            bit[pos] += x, pos += pos&-pos;
        }
    }
    int last_smaller(int x) {
        int pos = 0;
        for (int i = lg; i >= 0; i--) {
            if (pos + (1 << i) <= n && x > bit[pos+(1<<i)]) {
                x -= bit[pos+(1<<i)];
                pos += 1<<i;
            }
        }
        return pos-1;
    }
};
int main() {
    cin.tie(0)->sync_with_stdio(0);
    int a, q;
    cin >> a >> q;
    vector<int> t(a);
    for (int &x : t) cin >> x;
    auto upd = [&](vector<int> &C) {
        vector<int> A(a/2), B(a/2), ret(a);
        for (int j = 0; j < a/2; j++) A[j] = C[j], B[j] = C[j+a/2];
        int ii = 0, jj = 0;
        for (int j = 0; j < a; j++) {
            if (ii == a/2) ret[j] = B[jj++];
            else if (jj == a/2) ret[j] = A[ii++];
            else {
                if (A[ii] < B[jj]) ret[j] = A[ii++];
                else ret[j] = B[jj++];
            }
        }
        swap(C, ret);
    };
    vector<int> orig_t(t);
    upd(t);
    vector<int> where(a+1);
    fenwick fw(a+1);
    for (int i = 0; i < a; i++) where[t[i]] = i;
    for (int i = 0; i < a; i++) {
        int r = i;
        while (r + 1 < a && t[r+1] <= t[i]) r++;
        fw.update(t[i], r-i+1);
        i = r;
    }
    vector<int> nxt(a, a);
    stack<ar<int, 2>> stk;
    for (int i = a-1; i >= 0; i--) {
        while (stk.size() && stk.top()[0] < t[i]) stk.pop();
        if (stk.size()) nxt[i] = stk.top()[1];
        stk.push({t[i], i});
    }
    vector<ar<int, 3>> queries(q);
    for (int i = 0; i < q; i++) {
        cin >> queries[i][0] >> queries[i][1];
        queries[i][2] = i;
    }
    sort(queries.begin(), queries.end());
    vector<int> ret(q);
    int time = 1;
    bool converged = 0;
    for (int i = 0; i < q; i++) {
        while (!converged && time < queries[i][0]) {
            int ans = fw.last_smaller(a/2) + 1;
            if (fw.pref(ans) == a/2) {
                converged = 1; break;
            }
            int l1 = where[ans] + a/2 - fw.pref(ans-1), r1 = where[ans] + fw.point(ans) - 1;
            int old_idx = fw.pref(ans-1), old_len = fw.point(ans);
            fw.update(ans, -old_len + a/2 - old_idx);
            while (l1 <= r1) {
                int nxt_ = min(r1, nxt[l1] - 1);
                //assert(fw.point(t[l1]) == 0);
                fw.update(t[l1], nxt_-l1+1);
                l1 = nxt_ + 1;
            }
            time++;
        }
        if (!queries[i][0]) ret[queries[i][2]] = orig_t[queries[i][1]-1];
        else {
            int idx = queries[i][1], ans = fw.last_smaller(idx) + 1;
            ret[queries[i][2]] = t[where[ans] + idx - fw.pref(ans-1) - 1];
        }
    }
    for (int i = 0; i < q; i++) cout << ret[i] << '\n';
}

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