Submission #391944

#	Time	Username	Problem	Language	Result	Execution time	Memory
391944		Jarif_Rahman	Index (COCI21_index)	C++17	110 / 110	1650 ms	12288 KiB

index

#include <bits/stdc++.h>
#define pb push_back
#define f first
#define sc second
using namespace std;
typedef long long int ll;
typedef string str;
const int sq = 417, lim = 524288;
bool mo(tuple<int, int, int> a, tuple<int, int, int> b){
    return make_pair(get<0>(a)/sq, get<1>(a)) < make_pair(get<0>(b)/sq, get<1>(b));
}
struct segtree{
    int k;
    ll sm[lim];
    segtree(int n){
        k = lim;
    }
    void upd(int in, ll x){
        in+=k/2;
        sm[in] = x, in/=2;
        while(in > 0){
            sm[in] = sm[2*in] + sm[2*in+1];
            in/=2;
        }
    }
    inline ll sum(int l, int r, int nd, int a, int b){
        if(b < l || a > r) return 0;
        if(a >= l && b <= r) return sm[nd];
        int c = (a+b)/2;
        return sum(l, r, 2*nd, a, c) + sum(l, r, 2*nd+1, c+1, b);
    }
    inline ll sum(int l, int r){
        return sum(l, r, 1, 0, k/2-1);
    }
    inline ll ans(int a, int b, int nd, ll s){
        if(nd >= k/2) return a;
        int md = (a+b)/2;
        if(s+sm[2*nd+1] >= md+1) return ans(md+1, b, 2*nd+1, s);
        return ans(a, md, 2*nd, s+sm[2*nd+1]);
    }
    ll get(int in){
        return sm[k/2+in];
    }
};
int main(){
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int n, q; cin >> n >> q;
    int v[n];
    for(int &x: v) cin >> x;
    tuple<int, int, int> query[q];
    for(int i = 0; i < q; i++){
        int l, r; cin >> l >> r; l--, r--;
        query[i] = {l, r, i};
    }
    vector<int> ans(q);
    sort(query, query+q, mo);
    segtree pp(lim);
    int a = 0, b = 0;
    pp.upd(v[0], pp.get(v[0])+1);
    for(auto [l, r, in]: query){
        for(int i = a; i < l; i++) pp.upd(v[i], pp.get(v[i])-1);
        for(int i = a-1; i >= l; i--) pp.upd(v[i], pp.get(v[i])+1);
        for(int i = b+1; i <= r; i++) pp.upd(v[i], pp.get(v[i])+1);
        for(int i = b; i > r; i--) pp.upd(v[i], pp.get(v[i])-1);
        a = l, b = r;
        ans[in] = pp.ans(0, pp.k/2-1, 1, 0);
    }
    for(int x: ans) cout << x << "\n";
}

Compilation message (stderr)

index.cpp: In function 'int main()':
index.cpp:42:25: warning: 'pp.segtree::sm[<unknown>]' may be used uninitialized in this function [-Wmaybe-uninitialized]
   42 |         return sm[k/2+in];
      |                         ^

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