Submission #836825

#	Time	Username	Problem	Language	Result	Execution time	Memory
836825		tengiz05	Radio Towers (IOI22_towers)	C++17	23 / 100	4037 ms	2632 KiB

towers

#include "towers.h"

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

vector<int> h;
int n;
void init(int N, vector<int> H) {
    n = N;
    h = H;
}

bool processed = false;
vector<int> nxt, dow;
int max_towers(int l, int r, int D) {
    if (!processed) {
        processed = true;
        deque<pair<int, int>> st;
        nxt.assign(n + 1, n);
        dow.assign(n + 1, n);
        for (int i = n - 1; i >= 0; i--) {
            while (!st.empty() && h[st.front().second] <= h[i]) st.pop_front();
            st.push_front({h[i], i});
            auto p = lower_bound(st.begin(), st.end(), pair{h[i] + D, -1});
            if (p != st.end()) {
                nxt[i] = p->second;
            }
        }
        for (int i = n - 2; i >= 0; i--) {
            nxt[i] = min(nxt[i], nxt[i + 1]);
        }
        st.clear();
        for (int i = n - 1; i >= 0; i--) {
            while (!st.empty() && h[st.back().second] >= h[i]) st.pop_back();
            st.push_back({h[i], i});
            auto p = lower_bound(st.begin(), st.end(), pair{h[i] - D + 1, -1});
            if (p != st.begin()) {
                p--;
                dow[i] = p->second;
            }
            // if (i == 2) {
                // cout << "the demosntration\n";
                // for (auto [x, y] : st) {
                    // cout << x << " ";
                // }
                // cout << "\n";
            // }
        }
        for (int i = n - 2; i >= 0; i--) {
            dow[i] = min(dow[i], dow[i + 1]);
        }
    }
    // for (int i = 0; i < n; i++) {
        // cout << nxt[i] << " " << dow[i] << "\n";
    // }
    int p = l;
    int s = 0;
    while (p < r) {
        if (s % 2 == 0) {
            p = nxt[p];
            if (p <= r) {
                s++;
            }
        } else {
            p = dow[p];
            if (p <= r) {
                s++;
            }
        }
    }
    return s / 2 + 1;
}

• 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