161 lines
3.0 KiB
C++
161 lines
3.0 KiB
C++
/* Problem URL: https://codeforces.com/group/YgJmumGtHD/contest/105936/problem/B */
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#include <bits/stdc++.h>
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using namespace std;
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#define V vector
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#define rmin(a, b) a = min(a, b)
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#define rmax(a, b) a = max(a, b)
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#define rep(i, lim) for (int i = 0; i < (lim); i++)
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#define nrep(i, s, lim) for (int i = s; i < (lim); i++)
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#define repv(i, v) for (auto &i : (v))
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#define fillv(v) for (auto &itr_ : (v)) { cin >> itr_; }
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#define sortv(v) sort(v.begin(), v.end())
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#define all(v) (v).begin(), (v).end()
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using vi = vector<int>;
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using vvi = vector<vi>;
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using vvvi = vector<vvi>;
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using vvvvi = vector<vvvi>;
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using ll = long long;
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using vl = vector<ll>;
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using vvl = vector<vl>;
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using vvvl = vector<vvl>;
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using vvvvl = vector<vvvl>;
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template<class v>
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auto operator<<(ostream &os, const vector<v> &vec)->ostream& {
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os << vec[0];
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for (size_t i = 1; i < vec.size(); i++) {
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os << ' ' << vec[i];
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}
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os << '\n';
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return os;
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}
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template<class v>
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auto operator>>(istream &is, vector<v> &vec)->istream& {
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for (auto &i : vec) {
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is >> i;
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}
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return is;
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}
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template<class v>
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auto operator<<(ostream &os, const vector<vector<v>> &vec)->ostream& {
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for (auto &i : vec) {
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os << i[0];
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for (size_t j = 1; j < i.size(); j++) {
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os << ' ' << i[j];
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}
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os << '\n';
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}
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return os;
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}
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template<class v>
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auto operator>>(istream &is, vector<vector<v>> &vec)->istream& {
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for (auto &i : vec) {
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for (auto &j : i) {
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is >> j;
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}
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}
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return is;
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}
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int main()
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{
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ios::sync_with_stdio(false);
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cin.tie(nullptr);
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int n;
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cin >> n;
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struct bar {
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int x;
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int t;
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bool operator<(bar &b) {
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if (t == b.t) {
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return x > b.x;
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}
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return t > b.t;
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}
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};
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V<bar> fds(n);
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repv(i, fds) {
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cin >> i.x >> i.t;
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}
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sortv(fds);
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map<int, vi> var;
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rep(i, n) {
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var[fds[i].t].push_back(i);
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}
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vi dp(n, -1);
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vi maximal(n, 0);
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const int inf = INT32_MAX >> 1;
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function<int(int)> dfs = [&](int i) {
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if (dp[i] != -1) {
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return dp[i];
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}
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maximal[i] = fds[i].t;
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int t = fds[i].t;
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int x = fds[i].x;
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dp[i] = 1;
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auto end = var.find(t);
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auto itr = prev(var.end());
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int limit = inf;
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while (itr != end && itr->first < limit) {
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repv(j, itr->second) {
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if (abs(fds[j].x - x) + fds[i].t > fds[j].t) {
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continue;
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}
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rmax(maximal[i], maximal[j]);
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rmax(dp[i], dfs(j) + 1);
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}
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rmin(limit, maximal[i]);
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if (itr->first <= limit) {
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itr--;
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continue;
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}
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itr = var.lower_bound(limit);
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if (itr != var.begin()) {
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itr--;
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}
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}
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return dp[i];
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};
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int ans = 0;
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rep(i, n) {
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rmax(ans, dfs(i));
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}
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cout << ans << '\n';
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}
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