Submission #953087

#	Time	Username	Problem	Language	Result	Execution time	Memory
953087		WonderfulWhale	IOI Fever (JOI21_fever)	C++17	11 / 100	417 ms	12892 KiB

fever

#include<bits/stdc++.h>
using namespace std;

#define int int64_t
#define pb push_back
#define pii pair<int, int>
#define st first
#define nd second
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()

int n;
namespace B2 {
const int MAXN = 100'009;
 
pii tab[MAXN];
int dis[MAXN];
int dir[MAXN];
vector<int> G[MAXN][4];
 
int f(int a, int b) {
	return tab[a].st-tab[b].st+tab[a].nd-tab[b].nd;
}
 
int dijkstra(int x, int x_dir) {
	fill(dis, dis+n, 1e9);
	int cnt = 0;
	dis[x] = 0;
	dir[x] = x_dir;
	priority_queue<pii, vector<pii>, greater<pii>> Q;
	Q.push({dis[x], x});
	while(sz(Q)) {
		auto [d_x, x] = Q.top();
		Q.pop();
		if(d_x!=dis[x]) continue;
		cnt++;
		for(int y:G[x][dir[x]]) {
			int d = f(x, y);
			if(d>d_x) continue;
			if(d<dis[y]) {
				dis[y] = d;
				dir[y] = (dir[x]+1)%4;
				Q.push({dis[y], y});
			}
		}
		for(int y:G[x][(dir[x]+1)%4]) {
			int d = f(x, y);
			if(d>d_x) continue;
			if(d<dis[y]) {
				dis[y] = d;
				int ndir = dir[x]-1;
				if(ndir<0) ndir+=4;
				dir[y] = ndir;
				Q.push({dis[y], y});
			}
		}
	}
	return cnt;
}
}
namespace B1 {

int dx[] = {0, 0, 1, -1};
int dy[] = {1, -1, 0, 0};


pii tab[10];
int dir[10];
int dis[10];
bool vis[10];

int ans = 0;

int check(int x, int y) {
	int d1 = abs(tab[x].st-tab[y].st);
	int d2 = abs(tab[x].nd-tab[y].nd);
	if(d1!=d2) return -1;
	pii p1 = {tab[x].st+dx[dir[x]]*d1, tab[x].nd+dy[dir[x]]*d1};
	pii p2 = {tab[y].st+dx[dir[y]]*d1, tab[y].nd+dy[dir[y]]*d1};
	if(p1!=p2) return -1;
	return d1;
}

void dijkstra() {
	// for(int i=0;i<n;i++) cerr << dir[i] << " ";
	// cerr << "\n";
	vector<int> v(n-1);
	iota(all(v), 1);
	do {
		int cnt = 1;
		vector<int> d(n-1, 1e9);
		for(int i=0;i<n-1;i++) {
			int x = check(v[i], 0);
			if(x!=-1) {
				d[i] = min(d[i], x);
			}
			for(int j=i-1;j>=0;j--) {
				int y = check(v[i], v[j]);
				if(y<d[j]) continue;
				d[i] = min(d[i], y);
			}
			if(d[i]<1e9) cnt++;
			else break;
		}
		ans = max(ans, cnt);
	} while(next_permutation(all(v)));
}
}

int32_t main() {
	ios_base::sync_with_stdio(false);
	cin.tie(NULL);
	
	cin >> n;
	if(n<=7) {
	for(int i=0;i<n;i++) {
		cin >> B1::tab[i].st >> B1::tab[i].nd;
	}
	for(int i=0;i<(1<<(2*n));i++) {
		for(int j=0;j<2*n;j+=2) {
			bool a = i&(1<<j);
			bool b = i&(1<<(j+1));
			B1::dir[j/2] = 2*a+b;
		}
		B1::dijkstra();
	}
	cout << B1::ans << "\n";
	return 0;
	}
	using namespace B2;
	for(int i=0;i<n;i++) {
		int a, b;
		cin >> a >> b;
		tab[i] = {a-b, a+b};
		// cerr << i << ": " << tab[i] << "\n";
	}
	for(int i=0;i<n;i++) {
		auto [a1, b1] = tab[i];
		for(int j=0;j<n;j++) {
			auto [a2, b2] = tab[j];
			if(a1>a2&&b1==b2) {
				G[i][0].pb(j);
			}
			if(a1==a2&&b2>b1) {
				G[i][1].pb(j);
			}
			if(a1<a2&&b1==b2) {
				G[i][2].pb(j);
			}
			if(a1==a2&&b2<b1) {
				G[i][3].pb(j);
			}
		}
	}
	int ans = 0;
	for(int i=0;i<4;i++) {
		ans = max(ans, dijkstra(0, i));
	}
	cout << ans << "\n";
}

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