Submission #838627

#	Time	Username	Problem	Language	Result	Execution time	Memory
838627		erekle	Radio Towers (IOI22_towers)	C++17	23 / 100	4078 ms	11572 KiB

towers

#include "towers.h"
#include <vector>
#include <algorithm>
#include <set>

using namespace std;

int n;
vector<int> H;
vector<pair<int, int>> byH;

const int MX_N = 1e5, LG = 17;
int rmq[1+LG][MX_N];
int p2[MX_N];
int rangeMax(int l, int r) {
    int p = p2[r-l+1];
    return max(rmq[p][l], rmq[p][r-(1<<p)+1]);
}
bool connected(int x, int y, int d) {
    if (x == y) return true;
    if (x > y) swap(x, y);
    if (x+1 == y) return false;
    return rangeMax(x+1, y-1) - d >= max(H[x], H[y]);
}

void init(int N, vector<int> Hs) {
    for (int i = 2; i <= N; ++i) p2[i] = p2[i-1] + !(i & (i-1));

    n = N, H = Hs;
    for (int i = 0; i < n; ++i) byH.emplace_back(H[i], i);
    sort(byH.begin(), byH.end());

    // rmq
    for (int i = 0; i < n; ++i) rmq[0][i] = H[i];
    for (int i = 1, p = 1; i <= LG; ++i, p <<= 1) {
        for (int j = 0; j < n; ++j) {
            if (j+p >= n) rmq[i][j] = rmq[i-1][j];
            else rmq[i][j] = max(rmq[i-1][j], rmq[i-1][j+p]);
        }
    }
}

int max_towers(int L, int R, int D) {
    set<int> included;
    for (auto [h, i] : byH) {
        if (i < L || i > R) continue;
        set<int>::iterator it = included.lower_bound(i);
        if (it != included.end() && !connected(i, *it, D)) continue;
        if (it != included.begin() && !connected(*prev(it), i, D)) continue;
        included.insert(i);
    }
    return included.size();
}

• 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