Submission #747787

#	Time	Username	Problem	Language	Result	Execution time	Memory
747787		MilosMilutinovic	Radio Towers (IOI22_towers)	C++17	17 / 100	902 ms	12736 KiB

towers

#include "towers.h"
#include <bits/stdc++.h>
using namespace std;
const int N = 1e5 + 10;
const int L = 22;
int n, a[N], pl[N], pr[N], ord[N];
bool cmp(int i, int j) { return a[i] < a[j]; }
int mx[N][L], logs[N];
int qmx(int l, int r) {
    int k = logs[r - l + 1];
    return max(mx[l][k], mx[r - (1 << k) + 1][k]);
}
void buildST() {
    for (int i = 1; i <= n; i++) mx[i][0] = a[i];
    for (int i = 2; i <= n; i++) logs[i] = logs[i >> 1] + 1;
    for (int j = 1; j < L; j++)
        for (int i = 1; i + (1 << j) <= n + 1; i++)
            mx[i][j] = max(mx[i][j - 1], mx[i + (1 << (j - 1))][j - 1]);
}
vector<int> qs;
void init(int N, vector<int> H) {
    n = N;
    for (int i = 1; i <= n; i++) a[i] = H[i - 1];
    vector <int> stk;
    for (int i = 1; i <= n; i++) {
        while (!stk.empty() && a[stk.back()] > a[i]) stk.pop_back();
        pl[i] = (stk.empty() ? -1 : stk.back());
        stk.push_back(i);
    }
    stk.clear();
    for (int i = n; i >= 1; i--) {
        while (!stk.empty() && a[stk.back()] > a[i]) stk.pop_back();
        pr[i] = (stk.empty() ? -1 : stk.back());
        stk.push_back(i);
    }
    buildST();
    for (int i = 1; i <= n; i++) ord[i] = i;
    sort(ord + 1, ord + n + 1, cmp);
    for (int _i = 2; _i <= n; _i++) {
        int i = ord[_i];
        int D = 1e9;
        if (pl[i] != -1) D = min(D, qmx(pl[i] + 1, i) - a[i]);
        if (pr[i] != -1) D = min(D, qmx(i, pr[i] - 1) - a[i]);
        qs.push_back(D);
//        printf("i=%d   delta->%d\n", i, D);
    }
    sort(qs.begin(), qs.end());
}
int max_towers(int L, int R, int D) {
    int res = 1 + qs.end() - lower_bound(qs.begin(), qs.end(), D);
    return res;
}

/*
7 1
10 20 60 40 50 30 70
0 6 17
*/

• 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