Submission #571630

#	Time	Username	Problem	Language	Result	Execution time	Memory
571630		dennisstar	Meetings (IOI18_meetings)	C++17	100 / 100	2913 ms	786432 KiB

meetings

#include "meetings.h"
#include <bits/stdc++.h>

using namespace std;
using ll = long long;

pair<int, int> st[1<<21];

vector<ll> minimum_costs(vector<int> H, vector<int> L, vector<int> R) {
	int n=H.size();
	vector<ll> ans(L.size(), 1e18);

	vector<array<int, 2>> ct(n, {-1, -1});
	vector<int> pr(n), lc(n, -1), rc(n, -1);
	int rt=0;
	for (int i=1, lst; i<n; i++) {
		lst=i-1;
		while (H[lst]<H[i]&&lst!=rt) lst=pr[lst];
		if (H[lst]<H[i]) pr[rt]=i, lc[i]=rt, rt=i;
		else if (rc[lst]==-1) rc[lst]=i, pr[i]=lst;
		else pr[rc[lst]]=i, lc[i]=rc[lst], rc[lst]=i, pr[i]=lst;
	}
	for (int i=0; i<n; i++) ct[i]={lc[i], rc[i]};

	for (int tr=0; tr<2; tr++) {
		vector<vector<int>> qu(n);

		memset(st, 0, sizeof(st));
		for (int i=0; i<n; i++) st[i+(1<<20)]={H[i], i*(tr?1:-1)};
		for (int i=(1<<20)-1; i; i--) st[i]=max(st[i*2], st[i*2+1]);
 
		auto getmx = [&](int l, int r) {
			l+=(1<<20);
			r+=(1<<20);
			pair<int, int> rt(0, 0);
			while (l<=r) {
				if (l%2) rt=max(rt, st[l]), l++;
				if (r%2==0) rt=max(rt, st[r]), r--;
				l/=2;
				r/=2;
			}
			return rt.second*(tr?1:-1);
		};

		for (int i=0; i<L.size(); i++) qu[getmx(L[i], R[i])].emplace_back(i);

		vector<ll> pl(n);
		vector<tuple<ll, ll, int, int>> sc(n);

		auto getv = [&](tuple<ll, ll, int, int> t, int x) {
			auto [a, b, l, r]=t;
			return a*x+b;
		};

		vector<deque<int>> nl(n);

		auto cal = [&](int u, int l) {
			auto calc = [&](int rb) {
				int s=0, e=nl[u].size()-1;
				while (s<e) {
					int m=(s+e)/2;
					if (get<3>(sc[nl[u][m]])<rb) s=m+1;
					else e=m;
				}
				return getv(sc[nl[u][s]], rb)+pl[u];
			};

			for (int i:qu[u]) ans[i]=min(ans[i], calc(R[i])-1ll*H[u]*(L[i]-l));
		};

		function<void(int)> dfs = [&](int u) {
			if (u==-1) return ;
			auto [l, r]=ct[u];
			dfs(l);
			dfs(r);
			int lb=u;
			if (l!=-1) swap(nl[l], nl[u]), pl[u]=pl[l], lb=get<2>(sc[nl[u][0]]);
			auto &ins = sc[u];
			ins={H[u], (nl[u].size()?getv(sc[nl[u].back()], u-1):0)+H[u]-1ll*u*H[u], u, u};
			while (nl[u].size()&&get<0>(sc[nl[u].back()])==H[u]) get<2>(ins)=get<2>(sc[nl[u].back()]), nl[u].pop_back();
			if (r==-1) {
				nl[u].emplace_back(u);
				for (int i:qu[u]) ans[i]=min(ans[i], 1ll*(R[i]-L[i]+1)*H[u]);
				return ;
			}
			pl[r]+=1ll*(u-lb+1)*H[u];
			swap(nl[r], nl[u]);
			swap(pl[r], pl[u]);
			cal(u, lb);
			swap(nl[r], nl[u]);
			swap(pl[r], pl[u]);

			while (nl[r].size()) {
				if (getv(sc[nl[r][0]], get<3>(sc[nl[r][0]]))+pl[r]>=getv(ins, get<3>(sc[nl[r][0]]))+pl[u]) get<3>(ins)=get<3>(sc[nl[r][0]]), nl[r].pop_front();
				else if (getv(sc[nl[r][0]], get<2>(sc[nl[r][0]]))+pl[r]<getv(ins, get<2>(sc[nl[r][0]]))+pl[u]) break;
				else {
					int s=get<2>(sc[nl[r][0]]), e=get<3>(sc[nl[r][0]]);
					while (s<e) {
						int m=(s+e+1)/2;
						if (getv(sc[nl[r][0]], m)+pl[r]>=getv(ins, m)+pl[u]) s=m;
						else e=m-1;
					}
					get<2>(sc[nl[r][0]])=s+1;
					get<3>(ins)=s;
					break;
				}
			}

			nl[u].emplace_back(u);
			if (nl[u].size()>=nl[r].size()) for (auto &i:nl[r]) get<1>(sc[i])+=pl[r]-pl[u], nl[u].emplace_back(i);
			else {
				reverse(nl[u].begin(), nl[u].end());
				for (auto &i:nl[u]) get<1>(sc[i])+=pl[u]-pl[r], nl[r].emplace_front(i);
				swap(nl[u], nl[r]);
				pl[u]=pl[r];
			}
		};
		dfs(rt);

		reverse(H.begin(), H.end());
		for (int i=0; i<L.size(); i++) tie(L[i], R[i])=make_pair(n-1-R[i], n-1-L[i]);
		rt=n-1-rt;
		for (auto &[l, r]:ct) tie(l, r)=make_pair(r==-1?-1:n-1-r, l==-1?-1:n-1-l);
		reverse(ct.begin(), ct.end());
	}

	return ans;
}

Compilation message (stderr)

meetings.cpp: In function 'std::vector<long long int> minimum_costs(std::vector<int>, std::vector<int>, std::vector<int>)':
meetings.cpp:28:27: warning: 'void* memset(void*, int, size_t)' clearing an object of type 'struct std::pair<int, int>' with no trivial copy-assignment; use assignment instead [-Wclass-memaccess]
   28 |   memset(st, 0, sizeof(st));
      |                           ^
In file included from /usr/include/c++/10/bits/stl_algobase.h:64,
                 from /usr/include/c++/10/vector:60,
                 from meetings.h:3,
                 from meetings.cpp:1:
/usr/include/c++/10/bits/stl_pair.h:211:12: note: 'struct std::pair<int, int>' declared here
  211 |     struct pair
      |            ^~~~
meetings.cpp:45:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   45 |   for (int i=0; i<L.size(); i++) qu[getmx(L[i], R[i])].emplace_back(i);
      |                 ~^~~~~~~~~
meetings.cpp:121:18: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<int>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
  121 |   for (int i=0; i<L.size(); i++) tie(L[i], R[i])=make_pair(n-1-R[i], n-1-L[i]);
      |                 ~^~~~~~~~~

• Subtask 1: 4 / 4
• Subtask 2: 15 / 15
• Subtask 3: 17 / 17
• Subtask 4: 24 / 24
• Subtask 5: 40 / 40