Submission #793897

#	Time	Username	Problem	Language	Result	Execution time	Memory
793897		ymm	IOI Fever (JOI21_fever)	C++17	25 / 100	5033 ms	46488 KiB

fever

#include <bits/stdc++.h>
#define Loop(x,l,r) for (ll x = (l); x < (r); ++x)
#define LoopR(x,l,r) for (ll x = (r)-1; x >= (l); --x)
typedef long long ll;
//typedef std::pair<int,int> pii;
using namespace std;

#define int ll

const int N = 100'010;
map<int,vector<int>> wa, as, sd, dw;
int X[N], Y[N];
int dis[N];
int n;

enum dir { W, A, S, D};
map<int,vector<int>> *dvec[4][2] = {
	{&dw, &wa},
	{&as, &wa},
	{&as, &sd},
	{&dw, &sd},
};

pair<int,dir> colide(int i, int j, dir d)
{
	int x = X[j] - X[i];
	int y = Y[j] - Y[i];
	assert(abs(x) == abs(y));
	switch (d) {
		case W: return {y, x > 0? A: D};
		case A: return {-x, y > 0? S: W};
		case S: return {-y, x > 0? A: D};
		case D: return {x, y > 0? S: W};
	}
}
dir disdir[N];

int dij(int v, dir d)
{
	fill(dis, dis+N, (ll)1e18);
	set<pair<int,int>> S;
	disdir[v] = d;
	dis[v] = 0;
	S.insert({dis[v], v});
	int ans = 0;
	while (S.size()) {
		++ans;
		int v = S.begin()->second;
		S.erase(S.begin());
		dir d = disdir[v];
		auto &vec1 = (*dvec[d][0])[X[v]-Y[v]];
		auto &vec2 = (*dvec[d][1])[X[v]+Y[v]];
		for (auto _vec : {&vec1, &vec2}) {
			auto &vec = *_vec;
			//while (vec.size()) {
			//	int u = vec.back();
			LoopR (i,0,vec.size()) {
				int u = vec[i];
				auto [di, d2] = colide(v, u, d);
				if (di < dis[v])
					break;
				if (di < dis[u]) {
					S.erase({dis[u], u});
					dis[u] = di;
					disdir[u] = d2;
					S.insert({dis[u], u});
				}
			}
		}
	}
	return ans;
	//return q.size();
}

signed main()
{
	cin.tie(0) -> sync_with_stdio(false);
	cin >> n;
	Loop (i,0,n)
		cin >> X[i] >> Y[i];
	Loop (i,1,n) {
		X[i] -= X[0];
		Y[i] -= Y[0];
	}
	X[0] = Y[0] = 0;
	int ans = 0;
	for (auto d : {W, A, S, D}) {
		for (auto mp : {&dw, &wa, &as, &sd})
			for (auto &[_, vec] : *mp)
				vec.clear();
		Loop (i,0,n) {
			dw[X[i]-Y[i]].push_back(i);
			wa[X[i]+Y[i]].push_back(i);
			as[X[i]-Y[i]].push_back(i);
			sd[X[i]+Y[i]].push_back(i);
		}
		for (auto &[_, vec] : dw) sort(vec.begin(), vec.end(), [&](int i, int j){ return X[i] < X[j]; });
		for (auto &[_, vec] : wa) sort(vec.begin(), vec.end(), [&](int i, int j){ return X[i] > X[j]; });
		for (auto &[_, vec] : as) sort(vec.begin(), vec.end(), [&](int i, int j){ return X[i] > X[j]; });
		for (auto &[_, vec] : sd) sort(vec.begin(), vec.end(), [&](int i, int j){ return X[i] < X[j]; });
		ans = max(ans, dij(0, d));
	}
	cout << ans << '\n';
}

Compilation message (stderr)

fever.cpp: In function 'std::pair<long long int, dir> colide(ll, ll, dir)':
fever.cpp:35:1: warning: control reaches end of non-void function [-Wreturn-type]
   35 | }
      | ^

• Subtask 1: 5 / 5
• Subtask 2: 8 / 8
• Subtask 3: 6 / 6
• Subtask 4: 6 / 6
• Subtask 5: 0 / 12
• Subtask 6: 0 / 32
• Subtask 7: 0 / 31