Submission #955172

#	Time	Username	Problem	Language	Result	Execution time	Memory
955172		shezitt	Index (COCI21_index)	C++17	110 / 110	1645 ms	140076 KiB

index

#include <iostream>
#include <algorithm>
#include <vector>
#include <cassert>

using namespace std;

using ll = long long;
#define int ll
#define sz(x) (int)x.size()
#define all(x) x.begin(), x.end()
#define raya cerr << "==================" << endl;

#define fore(i, a, b) for(int i=a; i<b; ++i)

const int N = 2e5+5;

int p[N], n, q;

int mp[N];

struct Node {
    Node *left, *right;
    int val;

    Node() {
        left = nullptr;
        right = nullptr;
        val = 0;
    }

};

int arr[N];

Node* version[N];

void init(Node *cur, int tl, int tr){
    if(tl == tr){
        cur->val = arr[tl];
        return;
    }

    int tm = (tl + tr) / 2;

    cur->left = new Node();
    cur->right = new Node();

    init(cur->left, tl, tm);
    init(cur->right, tm+1, tr);

    cur->val = cur->left->val + cur->right->val;

}

void update(Node *cur, Node *prev, int tl, int tr, int idx, int val){
    if(tl == tr){
        arr[tl] = val;
        cur->val = val;
        return;
    }

    int tm = (tl + tr) / 2;

    if(idx <= tm){
        cur->left = new Node();
        cur->right = prev->right;
        update(cur->left, prev->left, tl, tm, idx, val);
    } else {
        cur->left = prev->left;
        cur->right = new Node();
        update(cur->right, prev->right, tm+1, tr, idx, val);
    }

    cur->val = cur->left->val + cur->right->val;

}

void update(Node *cur, Node *prev, int idx, int val){
    update(cur, prev, 0, N-1, idx, val);
}

int query(Node *cur, int tl, int tr, int l, int r){
    if(l <= tl && tr <= r){
        return cur->val;
    }

    if(r < tl or tr < l){
        return 0;
    }

    int tm = (tl + tr) / 2;

    int p1 = query(cur->left, tl, tm, l, r);
    int p2 = query(cur->right, tm+1, tr, l, r);

    return p1 + p2;

}

int query(Node *cur, int l, int r){
    return query(cur, 0, N-1, l, r);
}

signed main(){
    cin >> n >> q;

    fore(i, 0, n){
        cin >> p[i];
    }

    // vector<int> sorted;
    // sorted.insert(sorted.begin(), p, p+n);

    // sort(all(sorted));
    // sorted.erase(unique(all(sorted)), sorted.end());

    // fore(i, 0, sz(sorted)){
    //     mp[sorted[i]] = i;
    // }

    version[0] = new Node();
    init(version[0], 0, N);

    fore(i, 0, n){
        version[i+1] = new Node();
        // int key = mp[p[i]];
        int prevVal = query(version[i], p[i], p[i]);
        update(version[i+1], version[i], p[i], prevVal + 1);
    }

    fore(i, 0, q){
        int l, r;
        cin >> l >> r;

        int low = 1, high = N;
        int res = -1;

        while(low <= high){
            int mid = low + (high - low) / 2;

            int cnt = query(version[r], mid, N-1) - query(version[l-1], mid, N-1);

            if(cnt >= mid){
                res = mid;
                low = mid+1;
            } else {
                high = mid-1;
            }

        }

        cout << res << endl;

        // vector<int> tmp;
        // tmp.insert(tmp.begin(), p+l-1, p+r);

        // sort(tmp.rbegin(), tmp.rend());

        // int low = 1, high = sz(tmp);
        // int res = -1;
        // while(low <= high){
        //     int mid = (low + high) / 2;
        //     if(tmp[mid-1] >= mid){
        //         res = mid;
        //         low = mid+1;
        //     } else {
        //         high = mid-1;
        //     }
        // }
        // assert( res > -1);
        // cout << res << endl;

    }

}

• Subtask 1: 20 / 20
• Subtask 2: 40 / 40
• Subtask 3: 50 / 50