Submission #1215309

#	Time	Username	Problem	Language	Result	Execution time	Memory
1215309		Nelt	Radio Towers (IOI22_towers)	C++20	23 / 100	4035 ms	7572 KiB

towers

#include "towers.h"
#include <bits/stdc++.h>
#define ll long long
#define endl "\n"
using namespace std;
const ll N = 1e5 + 5, inf = 2e18;
ll a[N], n, lef[N], rig[N];
void init(int N, vector<int> H)
{
    n = N;
    for (ll i = 1; i <= n; i++)
        a[i] = H[i - 1];
}

int max_towers(int l, int r, int d)
{
    l++, r++;
    vector<pair<ll, ll>> st;
    for (ll i = l; i <= r; i++)
    {
        while (!st.empty() and a[i] > st.back().first) st.pop_back();
        auto pos = lower_bound(st.begin(), st.end(), make_pair(a[i] + d - 1, inf), greater());
        if (pos == st.begin()) lef[i] = l - 1;
        else lef[i] = (pos - 1)->second;
        st.push_back(make_pair(a[i], i));
    }
    while (!st.empty()) st.pop_back();
    for (ll i = r; i >= l; i--)
    {
        while (!st.empty() and a[i] > st.back().first) st.pop_back();
        auto pos = lower_bound(st.begin(), st.end(), make_pair(a[i] + d - 1, inf), greater());
        if (pos == st.begin()) rig[i] = r + 1;
        else rig[i] = (pos - 1)->second;
        st.push_back(make_pair(a[i], i));
    }
    vector<pair<ll, ll>> segs;
    for (ll i = l; i <= r; i++) segs.push_back(make_pair(rig[i], lef[i]));
    sort(segs.begin(), segs.end());
    ll cur = -1, ans = 0;
    for (auto [r, l] : segs) 
        if (l >= cur) cur = r, ans++;
    return ans;
}

• Subtask 1: 0 / 4
• Subtask 2: 11 / 11
• Subtask 3: 12 / 12
• Subtask 4: 0 / 14
• Subtask 5: 0 / 17
• Subtask 6: 0 / 19
• Subtask 7: 0 / 23