Submission #1074197

#TimeUsernameProblemLanguageResultExecution timeMemory
1074197Gromp15Radio Towers (IOI22_towers)C++17
23 / 100
480 ms4072 KiB
#include <bits/stdc++.h> #include "towers.h" #define ll long long #define ar array #define sz(x) (int)x.size() #define all(x) x.begin(), x.end() using namespace std; template<typename T> bool ckmin(T &a, const T &b ) { return a > b ? a = b, 1 : 0; } template<typename T> bool ckmax(T &a, const T &b ) { return a < b ? a = b, 1 : 0; } int n; vector<int> h, h2, pref; void init(int N, std::vector<int> H) { n = N; h = H; h2 = H; sort(all(h2)); h2.erase(unique(all(h2)), h2.end()); for (int &x : h) x = lower_bound(all(h2), x) - h2.begin(); pref.resize(n); for (int i = 0; i < n; i++) { int r = i; while (r+1 < n && h[r+1] > h[r]) r++; pref[i]++, i = r; } for (int i = 1; i < n; i++) pref[i] += pref[i-1]; } struct seg { int N; vector<int> tree; seg(int n) : N(1<<(__lg(n)+1)), tree(2*N, -1e9) {} void update(int pos, int x) { for (int i = pos + N; i; i >>= 1) ckmax(tree[i], x); } int query(int node, int nl, int nr, int ql, int qr) { if (ql > nr || qr < nl) return -1e9; if (ql <= nl && nr <= qr) return tree[node]; int mid = (nl+nr)/2; return max(query(node*2, nl, mid, ql, qr), query(node*2+1, mid+1, nr, ql, qr)); } int query(int l, int r) { return query(1, 0, N-1, l, r); } }; int Q = 0; int max_towers(int L, int R, int D) { if (Q++ == 0) { const int N = sz(h2); seg st0(N), st1(N); for (int i = L; i <= R; i++) { auto it = lower_bound(all(h2), h2[h[i]] + D); if (it != h2.end()) { st1.update(h[i], st0.query(it - h2.begin(), N - 1) + 1); } auto it2 = upper_bound(all(h2), h2[h[i]] - D); if (it2 != h2.begin()) { it2--; st0.update(h[i], st1.query(0, it2 - h2.begin())); } st1.update(h[i], 1); } return st1.query(0, N-1); } return pref[R] - pref[L] + 1; }
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