Submission #1059767

#	Time	Username	Problem	Language	Result	Execution time	Memory
1059767		becaido	Radio Towers (IOI22_towers)	C++17	17 / 100	811 ms	12020 KiB

towers

#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx,popcnt,sse4,abm")
#include <bits/stdc++.h>
using namespace std;

#ifndef WAIMAI
#include "towers.h"
#else
#include "stub.cpp"
#endif

#ifdef WAIMAI
#define debug(HEHE...) cout << "[" << #HEHE << "] : ", dout(HEHE)
void dout() {cout << '\n';}
template<typename T, typename...U>
void dout(T t, U...u) {cout << t << (sizeof...(u) ? ", " : ""), dout(u...);}
#else
#define debug(...) 7122
#endif

#define ll long long
#define Waimai ios::sync_with_stdio(false), cin.tie(0)
#define FOR(x,a,b) for (int x = a, I = b; x <= I; x++)
#define pb emplace_back
#define F first
#define S second

const int INF = 2e9 + 1;
const int SIZE = 1e5 + 5;

int n;
int a[SIZE], ty[SIZE];
vector<pair<int, int>> ans;

void init(int N, vector<int> H) {
    n = N;
    if (n == 1) return;
    FOR (i, 1, n) a[i] = H[i - 1];
    FOR (i, 1, n) {
        if ((i == 1 || a[i] < a[i - 1]) && (i == n || a[i] < a[i + 1])) ty[i] = 1;
        if ((i == 1 || a[i] > a[i - 1]) && (i == n || a[i] > a[i + 1])) ty[i] = 2;
    }
    set<int> s;
    multiset<pair<int, int>> ms;
    for (int i = 1, x = 1; i <= n; i++) if (ty[i] == x) {
        s.insert(i);
        x ^= 3;
    }
    if (ty[*s.rbegin()] == 2) s.erase(*s.rbegin());
    a[0] = a[n + 1] = INF;
    s.insert(0), s.insert(n + 1);
    ans.pb(0, s.size() / 2);
    bool f = 0;
    for (auto it = s.begin(); it != s.end(); it++) {
        f ^= 1;
        if (f == 0) continue;
        int i = *it;
        if (it != s.begin()) {
            int l = *prev(it);
            ms.emplace(a[i] - a[l], i);
        }
        if (next(it) != s.end()) {
            int r = *next(it);
            ms.emplace(a[i] - a[r], i);
        }
    }
    while (s.size() > 3) {
        int d = ms.begin()->F;
        while (ms.size() && ms.begin()->F == d) {
            auto [_, i] = *ms.begin();
            auto it = s.lower_bound(i), lit = prev(it), rit = next(it);
            int l = *lit, r = *rit;
            int il = *prev(lit), ir = *next(rit);
            if (a[l] > a[r]) {
                ms.erase(ms.find({a[i] - a[l], i}));
                ms.erase(ms.find({a[il] - a[l], il}));
                if (a[i] < a[il]) {
                    ms.erase({a[i] - a[r], i});
                    ms.emplace(a[il] - a[r], il);
                    s.erase(i);
                } else {
                    int j = *prev(s.find(il));
                    ms.erase(ms.find({a[il] - a[j], il}));
                    ms.emplace(a[i] - a[j], i);
                    s.erase(il);
                }
                s.erase(l);
            } else {
                ms.erase(ms.find({a[i] - a[r], i}));
                ms.erase(ms.find({a[ir] - a[r], ir}));
                if (a[i] < a[ir]) {
                    ms.erase({a[i] - a[l], i});
                    ms.emplace(a[ir] - a[l], ir);
                    s.erase(i);
                } else {
                    int j = *next(s.find(ir));
                    ms.erase(ms.find({a[ir] - a[j], ir}));
                    ms.emplace(a[i] - a[j], i);
                    s.erase(ir);
                }
                s.erase(r);
            }
        }
        ans.pb(d + 1, s.size() / 2);
    }
}

int max_towers(int L, int R, int D) {
    L++, R++;
    if (L == R) return 1;
    int i = lower_bound(ans.begin(), ans.end(), make_pair(D + 1, 0)) - ans.begin() - 1;
    return ans[i].S;
}

/*
in1
7 3
10 20 60 40 50 30 70
1 5 10
2 2 100
0 6 17
out1
3
1
2
*/

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