Submission #1110735

#	Time	Username	Problem	Language	Result	Execution time	Memory
1110735		luvna	Index (COCI21_index)	C++14	110 / 110	425 ms	23252 KiB

index

#include<bits/stdc++.h>

#define all(v) v.begin(), v.end()
#define endl "\n"

using namespace std;

const int N = 2e5 + 15;

int n, q;
int a[N];
int L[N], R[N];
vector<int> candidate[N];
vector<int> evt;
int bit[N];
pair<int,int> qu[N];
int ans[N];

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

int get(int l, int r){int res = 0; l--;
    for(;r; r -= (r & (-r))) res += bit[r];
    for(;l; l -= (l & (-l))) res -= bit[l];
    return res;
}

void solve(){
    cin >> n >> q;

    for(int i = 1; i <= n; i++) cin >> a[i], evt.push_back(i);

    sort(all(evt), [&](int x, int y){
        return a[x] > a[y];
    });

    for(int i = 1; i <= q; i++){
        int l, r; cin >> l >> r;
        qu[i] = {l,r};
        L[i] = 1, R[i] = r - l + 1;
    }

    while(true){
        bool any = false;
        for(int i = 1; i <= q; i++){
            if(L[i] > R[i]) continue;
            int mid = (L[i] + R[i]) >> 1;
            candidate[mid].push_back(i);
            any = true;
        }
        if(!any) break;
        for(int mid = n, j = 0; mid >= 1; mid--){
            while(j < evt.size() && a[evt[j]] >= mid){
                update(evt[j],1);
                j++;
            }
            for(int i : candidate[mid]){
                if(get(qu[i].first,qu[i].second) >= mid){
                    ans[i] = mid;
                    L[i] = mid+1;
                }
                else R[i] = mid-1;
            }
            candidate[mid].clear();
        }
        for(int i = 1; i <= n; i++) bit[i] = 0;
    }

    for(int i = 1; i <= q; i++) cout << ans[i] << endl;
}

signed main(){
    ios_base::sync_with_stdio(NULL);
    cin.tie(0); cout.tie(0);

    #define task "task"

    if(fopen(task".INP", "r")){
        freopen(task".INP", "r", stdin);
        freopen(task".OUT", "w", stdout);
    }

    int t; t = 1; //cin >> t;
    while(t--) solve();
}

Compilation message (stderr)

index.cpp: In function 'void solve()':
index.cpp:54:21: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   54 |             while(j < evt.size() && a[evt[j]] >= mid){
      |                   ~~^~~~~~~~~~~~
index.cpp: In function 'int main()':
index.cpp:80:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   80 |         freopen(task".INP", "r", stdin);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~
index.cpp:81:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
   81 |         freopen(task".OUT", "w", stdout);
      |         ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~

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