Submission #975728

#	Time	Username	Problem	Language	Result	Execution time	Memory
975728		starchan	Port Facility (JOI17_port_facility)	C++17	22 / 100	359 ms	319720 KiB

port_facility

#include<bits/stdc++.h>
using namespace std;
#define int long long
#define in array<int, 2>
#define pb push_back
#define pob pop_back
#define fast() ios_base::sync_with_stdio(false); cin.tie(NULL)

const int SMX = 1e6+5;
const int MX = 2e6+3;
const int mod = 1e9+7;

int vv[MX]; vector<vector<int>> g;

int leaf[MX];
vector<int> lleft;
vector<int> rright;
vector<bool> tree;
int nxt = 0;

int root[SMX];

int New()
{
	lleft.pb(-1); rright.pb(-1); g.resize(g.size()+1); tree.pb(0);
	return nxt++;
}

int build(int l, int r)
{
	int id = New(); int m = (l+r)/2;
	if(l==r)
		return id;
	lleft[id] = build(l, m); rright[id] = build(m+1, r);  tree[id] = 0;
	return id;
}

int upd(int pos, int id, int l, int r)
{
	int id_n = New(); tree[id_n] = 1;
	if(l == r)
		return leaf[pos] = id_n;
	lleft[id_n] = lleft[id]; rright[id_n] = rright[id];
	int m = (l+r)/2;
	if(pos <= m)
		lleft[id_n] = upd(pos, lleft[id], l, m);
	else
		rright[id_n] = upd(pos, rright[id], m+1, r);
	return id_n;
}

void add(int pp, int ql, int qr, int id, int l, int r)
{
	if(qr < l || r < ql)
		return;
	if((ql <= l) && (r <= qr))
	{
		g[pp].pb(id);
		return;
	}
	int m = (l+r)/2;
	add(pp, ql, qr, lleft[id], l, m);
	add(pp, ql, qr, rright[id], m+1, r);
	return;
}

vector<int> pa, col; bool works = true;

int leader(int u)
{
	if(pa[u] < 0)
		return u;
	else
	{
		int p = leader(pa[u]);
		col[u]^=col[pa[u]];
		return pa[u] = p;
	}
}

void merge(int u, int v, int xr)
{
	int x = leader(u);
	int y = leader(v);
	if(x == y)
	{
		if(col[u]^col[v]^xr)
			works = false;
		return;
	}
	if(pa[x] < pa[y])
	{
		swap(x, y);
		swap(u, v);
	}
	pa[y]+=pa[x];
	pa[x] = y;
	col[x] = col[u]^col[v]^xr;
	return;
}

vector<bool> rl(MX);
bool vis[MX];

void dfs(int u)
{
	vis[u] = 1;
	if(lleft[u] != -1)
	{
		if((!vis[lleft[u]]) && tree[lleft[u]])
			dfs(lleft[u]);
		if((!vis[rright[u]]) && tree[rright[u]])
			dfs(rright[u]);
		if(tree[lleft[u]]){
		//cout << "cat_L_Calling " << lleft[u] << " from " << u << endl;
		merge(u, lleft[u], 0);}
		if(tree[rright[u]]){
		//cout << "cat_R_Calling " << rright[u] << " from " << u << endl;
		merge(u, rright[u], 0);}
		return;
	}
	for(int v: g[u])
	{
		if(!tree[v])
			continue;
		merge(u, v, 1);
		if(vis[v])
		{
			//cout << "Tried to call " << v << " from " << u << endl;
			continue;
		}
		//cout << "Calling " << v << " from " << u <<  "\n";
		dfs(v);
	}
	return;
}

bool ppl[MX];

signed main()
{
	fast();//During debugging, this should ideally be removed.
	int n;
	cin >> n;
	for(int i = 1; i <= n; i++)
	{
		int x, y; cin >> x >> y;
		vv[x] = y;
	}
	int sn = 0; root[sn] = build(1, 2*n); //cout << "nxt = " << nxt << endl;

	int b[n+1];
	for(int i = 1; i <= 2*n; i++)
	{
		if(vv[i])
		{
			int p = upd(vv[i], root[sn++], 1, 2*n); root[sn] = p;
			add(leaf[vv[i]], i, vv[i]-1, p, 1, 2*n); rl[vv[i]] = 1;
			b[sn] = leaf[vv[i]];
			//cout << "b[sn] = " << b[sn] << endl;
		}
	}

	int N = g.size(); pa.assign(N, -1); col.assign(N, 0);
	for(int i = 1; i <= n; i++)
		dfs(b[i]);
	if(!works)
	{
		cout << "0\n";
		return 0;
	}
	int ans = 1;
	for(int i = 1; i <= n; i++)
	{
		if(ppl[leader(b[i])])
			continue;
		ppl[leader(b[i])] = 1; ans*=2; ans%=mod;
	}
	cout << ans << "\n";
	return 0;
}	

• Subtask 1: 10 / 10
• Subtask 2: 12 / 12
• Subtask 3: 0 / 56
• Subtask 4: 0 / 22