Submission #923114

#	Time	Username	Problem	Language	Result	Execution time	Memory
923114		GrindMachine	Abracadabra (CEOI22_abracadabra)	C++17	100 / 100	694 ms	66332 KiB

Main

#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T> using Tree = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long int ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

#define fastio ios_base::sync_with_stdio(false); cin.tie(NULL)
#define pb push_back
#define endl '\n'
#define sz(a) (int)a.size()
#define setbits(x) __builtin_popcountll(x)
#define ff first
#define ss second
#define conts continue
#define ceil2(x,y) ((x+y-1)/(y))
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define yes cout << "Yes" << endl
#define no cout << "No" << endl

#define rep(i,n) for(int i = 0; i < n; ++i)
#define rep1(i,n) for(int i = 1; i <= n; ++i)
#define rev(i,s,e) for(int i = s; i >= e; --i)
#define trav(i,a) for(auto &i : a)

template<typename T>
void amin(T &a, T b) {
    a = min(a,b);
}

template<typename T>
void amax(T &a, T b) {
    a = max(a,b);
}

#ifdef LOCAL
#include "debug.h"
#else
#define debug(x) 42
#endif

/*

read the edi a long time ago and remember some ideas from there

*/

const int MOD = 1e9 + 7;
const int N = 1e5 + 5;
const int inf1 = int(1e9) + 5;
const ll inf2 = ll(1e18) + 5;

template<typename T>
struct fenwick {
    int siz;
    vector<T> tree;

    fenwick() {

    }

    fenwick(int n) {
        siz = n;
        tree = vector<T>(n + 1);
    }

    int lsb(int x) {
        return x & -x;
    }

    void build(vector<T> &a, int n) {
        for (int i = 1; i <= n; ++i) {
            int par = i + lsb(i);
            tree[i] += a[i];

            if (par <= siz) {
                tree[par] += tree[i];
            }
        }
    }

    void pupd(int i, T v) {
        while (i <= siz) {
            tree[i] += v;
            i += lsb(i);
        }
    }

    T sum(int i) {
        T res = 0;

        while (i) {
            res += tree[i];
            i -= lsb(i);
        }

        return res;
    }

    T query(int l, int r) {
        if (l > r) return 0;
        T res = sum(r) - sum(l - 1);
        return res;
    }
};

void solve(int test_case)
{
    ll n,q; cin >> n >> q;
    vector<ll> a(n+5);
    rep1(i,n) cin >> a[i];

    vector<ll> rx(n+5,n);
    stack<ll> stk;
    rep1(i,n){
        while(!stk.empty() and a[i] > a[stk.top()]){
            rx[stk.top()] = i-1;
            stk.pop();
        }
        stk.push(i);
    }

    vector<ll> pos(n+5);
    rep1(i,n) pos[a[i]] = i;

    fenwick<ll> fenw(n+5);
    ll curr_mx = 0;

    rep1(i,n){
        if(a[i] > curr_mx){
            fenw.pupd(a[i],rx[i]-i+1);
            curr_mx = a[i];
        }
    }

    vector<pll> queries[n+5];
    rep1(id,q){
        ll t,i; cin >> t >> i;
        amin(t,n);
        queries[t].pb({i,id});
    }

    vector<ll> ans(q+5);

    rep(t,n+1){
        if(t){
            ll l = 1, r = n;
            ll mid_block = -1;

            while(l <= r){
                ll mid = (l+r) >> 1;
                if(fenw.query(1,mid) > n/2){
                    mid_block = mid;
                    r = mid-1;
                }
                else{
                    l = mid+1;
                }
            }

            assert(mid_block != -1);

            ll prev_sum = fenw.query(1,mid_block-1);
            ll ignore = n/2-prev_sum;

            if(ignore){
                ll siz = fenw.query(mid_block,mid_block);
                fenw.pupd(mid_block,-siz+ignore);

                ll ptr = pos[mid_block]+ignore;
                ll mxr = pos[mid_block]+siz-1;

                while(ptr <= mxr){
                    if(rx[ptr] <= mxr){
                        fenw.pupd(a[ptr],rx[ptr]-ptr+1);
                        ptr = rx[ptr]+1;
                    }
                    else{
                        fenw.pupd(a[ptr],mxr-ptr+1);
                        ptr = mxr+1;
                    }
                }
            }
        }

        for(auto [i,id] : queries[t]){
            ll l = 1, r = n;
            ll block = -1;

            while(l <= r){
                ll mid = (l+r) >> 1;
                if(fenw.query(1,mid) >= i){
                    block = mid;
                    r = mid-1;
                }
                else{
                    l = mid+1;
                }
            }

            ll prev_sum = fenw.query(1,block-1);
            ans[id] = a[pos[block]+i-prev_sum-1];
        }
    }

    rep1(i,q) cout << ans[i] << endl;
}

int main()
{
    fastio;

    int t = 1;
    // cin >> t;

    rep1(i, t) {
        solve(i);
    }

    return 0;
}

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