Submission #825003

#	Time	Username	Problem	Language	Result	Execution time	Memory
825003		PixelCat	Radio Towers (IOI22_towers)	C++17	23 / 100	4096 ms	4632 KiB

towers

#include "towers.h"

#ifdef NYAOWO
#include "stub.cpp"
#endif

#include <bits/stdc++.h>
#define For(i, a, b) for(int i = a; i <= b; i++)
#define Forr(i, a, b) for(int i = a; i >= b; i--)
#define F first
#define S second 
#define all(x) x.begin(), x.end()
#define sz(x) ((int)x.size())
#define eb emplace_back
// #define int LL
using namespace std;
using i32 = int32_t;
using LL = long long;
using pii = pair<int, int>;

inline void chmax(int &x, int val) { x = max(x, val); }

const int MAXN = 100'000;

#define L(id) ((id) * 2 + 1)
#define R(id) ((id) * 2 + 2)
struct SegTree {
    int mx[MAXN * 4 + 10];
    void build() {
        memset(mx, 0, sizeof(mx));
    }
    void upd(int id, int l, int r, int pos, int val) {
        if(l == r) {
            chmax(mx[id], val);
            return;
        }
        int m = (l + r) / 2;
        if(pos <= m) upd(L(id), l, m, pos, val);
        else         upd(R(id), m + 1, r, pos, val);
        mx[id] = max(mx[L(id)], mx[R(id)]);
    }
    int range_max(int id, int l, int r, int L, int R) {
        if(L > R) return 0;
        if(l >= L && r <= R) {
            return mx[id];
        }
        int m = (l + r) / 2;
        int res = 0;
        if(L <= m) chmax(res, range_max(L(id), l, m, L, R));
        if(R > m)  chmax(res, range_max(R(id), m + 1, r, L, R));
        return res;
    }
} dp1, dp2;

int n;
int h[MAXN + 10];
int vals[MAXN + 10];

void init(int N, std::vector<int> H) {
    n = N;
    For(i, 0, n - 1) {
        h[i] = H[i];
        vals[i] = h[i];
    }
    sort(vals, vals + n);
}

int max_towers(int L, int R, int D) {
    int ans = 0;
    dp1.build();
    dp2.build();
    For(i, L, R) {
        int p = (int)(lower_bound(vals, vals + n, h[i]) - vals);
        int l = (int)(upper_bound(vals, vals + n, h[i] - D) - vals) - 1;
        int r = (int)(lower_bound(vals, vals + n, h[i] + D) - vals);
        int v1 = dp2.range_max(0, 0, n - 1, r, n - 1) + 1;
        int v2 = dp1.range_max(0, 0, n - 1, 0, l);
        dp1.upd(0, 0, n - 1, p, v1);
        dp2.upd(0, 0, n - 1, p, v2);
        chmax(ans, v1);
    }
    return ans;
}

/*

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

3
1
2

*/

• 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