Submission #1266408

#	Time	Username	Problem	Language	Result	Execution time	Memory
1266408		CodeLakVN	Index (COCI21_index)	C++20	110 / 110	359 ms	38072 KiB

index

#include <bits/stdc++.h>
using namespace std;

#define task "main"
#define F first
#define S second
#define ii pair<int, int>
#define il pair<int, long long>
#define li pair<long long, int>
#define FOR(i, a, b) for(int i = (a); i <= (b); ++i)
#define FOD(i, b, a) for(int i = (b); i >= (a); --i)

template <class T1, class T2>
    bool maximize(T1 &a, T2 b){
        if (a < b) {a = b; return true;}
        return false;
    }

template <class T1, class T2>
    bool minimize(T1 &a, T2 b){
        if (a > b) {a = b; return true;}
        return false;
    }

template <class T>
    void printArr(T container, string separator = " ", string finish = "\n", ostream &out = cout){
        for(auto item: container) out << item << separator;
        out << finish;
    }

const int MAX_N = (int)2e5 + 5;

int n, q, mx;
int a[MAX_N];
ii queries[MAX_N];

namespace sub1 {
    bool check(int val, int l, int r) {
        int cnt = 0;
        FOR(i, l, r) cnt += a[i] >= val;
        return cnt >= val;
    }

    void solve() {
        FOR(i, 1, q) {
            int res = -1, l = 1, r = mx;
            while (l <= r) {
                int mid = (l + r) >> 1;
                if (check(mid, queries[i].F, queries[i].S)) l = (res = mid) + 1;
                else r = mid - 1;
            }

            cout << res << "\n";
        }
    }
}

namespace sub3 {
    vector<int> pos[MAX_N];

    struct BIT {
        int bit[MAX_N];

        void init() {
            FOR(i, 1, n) bit[i] = 0;
        }

        void update(int idx) {
            for (; idx <= n; idx += (idx & -idx))
                bit[idx]++;
        }

        int get(int idx) {
            int res = 0;
            for (; idx > 0; idx -= (idx & -idx))
                res += bit[idx];
            return res;
        }

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

    int l[MAX_N], r[MAX_N], res[MAX_N];
    vector<int> bucket[MAX_N];

    void solve() {
        FOR(i, 1, n) pos[a[i]].push_back(i);
        FOR(i, 1, q) l[i] = 1, r[i] = mx;

        while (true) {
            FOR(i, 1, mx) bucket[i].clear();

            bool isEmpty = 1;
            FOR(i, 1, q) if (l[i] <= r[i]) {
                int mid = (l[i] + r[i]) >> 1;
                bucket[mid].push_back(i);
                isEmpty = 0;
            }

            if (isEmpty) break;

            bit.init();
            FOD(x, mx, 1) {
                for (int i : pos[x]) bit.update(i);
                for (int i : bucket[x]) {
                    if (bit.get(queries[i].F, queries[i].S) >= x)
                        l[i] = (res[i] = x) + 1;
                    else
                        r[i] = x - 1;
                }
            }
        }

        FOR(i, 1, q) cout << res[i] << "\n";
    }
}

void solve() {
    cin >> n >> q;
    FOR(i, 1, n) cin >> a[i];
    FOR(i, 1, q) cin >> queries[i].F >> queries[i].S;

    mx = *max_element(a + 1, a + n + 1);

    if (max(n, q) <= 1000) sub1::solve();
    else sub3::solve();
}

int32_t main() {
    if (fopen(task".inp", "r")) {
        freopen(task".inp", "r", stdin);
        freopen(task".out", "w", stdout);
    }
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);

    bool multitest = 0;
    int numTest = 1;
    if (multitest) cin >> numTest;

    while (numTest--) {
        solve();
    }

    return 0;
}

/* Lak lu theo dieu nhac!!!! */

Compilation message (stderr)

index.cpp: In function 'int32_t main()':
index.cpp:133:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  133 |         freopen(task".inp", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
index.cpp:134:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
  134 |         freopen(task".out", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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