Submission #673199

#TimeUsernameProblemLanguageResultExecution timeMemory
673199US3RN4M3Event Hopping (BOI22_events)C++17
0 / 100
344 ms32588 KiB
#include<bits/stdc++.h> using namespace std; using ll = long long; const int mx = 100005; const int inf = 1e9; int n, q; pair<int, int> intervals[mx]; int ans[mx]; struct qd { set<pair<int, pair<int, int>>> qs; int cost; qd() { cost = 0; } void ins(pair<int, int> p) { qs.insert({p.first, {0, p.second}}); } void merge(qd & oth) { int delta = oth.cost - cost; for(auto p : oth.qs) { qs.insert({p.first, {p.second.first + delta, p.second.second}}); } } void sync(int i) { auto lim = qs.lower_bound({i + 1, {0, 0}}); for(auto it = qs.begin(); it != lim; it = qs.erase(it)) { ans[it->second.second] = cost + it->second.first; } } }; qd data0[mx]; struct st { pair<int, int> best; st * l; st * r; int size; st() {} st(int sz, int i) { size = sz; if(size > 1) { l = new st(size/2, i); r = new st((size + 1)/2, i + (size/2)); best = max(l->best, r->best); } else { best = {intervals[i].second, i}; } } pair<int, int> get(int s, int e) { /* [l, r) */ s = max(0, s); e = min(e, size); if(s == 0 && e == size) return best; pair<int, int> res = {0, 0}; if(s < l->size) res = max(res, l->get(s, e)); if(e > l->size) res = max(res, r->get(s - l->size, e - l->size)); return res; } }; st tree; int get_idx(int i) { int a = 0; for(int delta = (1<<18); delta >= 1; delta >>= 1) { int tmp = a + delta; if(tmp >= n) continue; if(intervals[tmp].first <= i) a = tmp; } return a; } main() { for(int i = 0; i < mx; i++) ans[i] = -1; cin >> n >> q; vector<pair<int, int>> orig(n); for(int i = 0; i < n; i++) { int s, e; cin >> s >> e; orig[i] = {s, e}; intervals[i] = {inf - e, inf - s}; } vector<pair<pair<int, int>, int>> order(n); for(int i = 0; i < n; i++) { order[i] = {{intervals[i].first, intervals[i].second}, i}; } sort(order.begin(), order.end()); vector<int> pos(n); for(int i = 0; i < n; i++) { pos[order[i].second] = i; } for(int i = 0; i < q; i++) { int s, e; cin >> e >> s; if(s == e) { ans[i] = 0; continue; } data0[pos[s - 1]].ins({intervals[e - 1].first, i}); } vector<pair<int, int>> tmp(n); for(int i = 0; i < n; i++) { tmp[i] = intervals[order[i].second]; } for(int i = 0; i < n; i++) { intervals[i] = tmp[i]; } tree = st(n, 0); for(int i = 0; i < n; i++) { int r = intervals[i].second; int dst_int = get_idx(r); data0[i].cost++; data0[i].sync(r); if(dst_int == i) continue; pair<int, int> next_best = tree.get(i + 1, dst_int + 1); int nidx = next_best.second; if(data0[i].qs.size() > data0[nidx].qs.size()) swap(data0[i], data0[nidx]); data0[nidx].merge(data0[i]); } for(int i = 0; i < q; i++) { if(ans[i] == -1) cout << "impossible" << endl; else cout << ans[i] << endl; } }

Compilation message (stderr)

events.cpp:68:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   68 | main() {
      | ^~~~
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