Submission #1039766

#	Time	Username	Problem	Language	Result	Execution time	Memory
1039766		Alihan_8	Fountain Parks (IOI21_parks)	C++17	70 / 100	1628 ms	136124 KiB

parks

#include "parks.h"
 
#include <bits/stdc++.h>
 
using namespace std;
 
#define all(x) x.begin(), x.end()
#define ar array
#define pb push_back
#define ln '\n'
//#define int long long
 
using i64 = long long;
 
template <class F, class _S>
bool chmin(F &u, const _S &v){
    bool flag = false;
    if ( u > v ){
        u = v; flag |= true;
    }
    return flag;
}
 
template <class F, class _S>
bool chmax(F &u, const _S &v){
    bool flag = false;
    if ( u < v ){
        u = v; flag |= true;
    }
    return flag;
}
 
struct Dsu{
	vector <int> fa;
	
	int n;
	
	Dsu(int n) : n(n) {
		fa.resize(n);
		iota(all(fa), 0);
	}
	
	int get(int u){
		return u ^ fa[u] ? fa[u] = get(fa[u]) : u;
	}
	
	bool merge(int u, int v){
		u = get(u), v = get(v);
		
		if ( u == v ) return false;
		
		fa[v] = u;
		
		return true;
	}
	
};

mt19937 rng(chrono::steady_clock().now().time_since_epoch().count());
#define rnd(l, r) uniform_int_distribution <int> (l, r)(rng)
 
int dx[] = {2, -2, 0, 0};
int dy[] = {0, 0, -2, 2};
 
int construct_roads(std::vector<int> x, std::vector<int> y) {
    int n = x.size();
    
    map <int,map<int,int>> id;
    
    for ( int i = 0; i < n; i++ ){
		id[x[i]][y[i]] = i;
	}
	
	vector <ar<int,2>> e, E;
	
	map <ar<int,2>,int> mp;
	
	vector <vector<int>> G(n);
	
	for ( int i = 0; i < n; i++ ){
		for ( int j = 0; j < 4; j++ ){
			int u = x[i] + dx[j], v = y[i] + dy[j];
			
			if ( !id[u].count(v) ) continue;
			
			E.pb({i, id[u][v]});
		}
	}
	
	auto f = [&](int i, int j){
		return y[i] == y[j];
	};
	
	sort(all(E), [&](auto &u, auto &v){
		auto [i, j] = u;
		auto [x_, y_] = v;
		
		if ( f(i, j) != f(x_, y_) ){
			return f(i, j) < f(x_, y_);
		}
		
		return y[i] < y[x_];
	});
	
	Dsu ds(n);
	
	for ( auto &[u, v]: E ){
		if ( ds.merge(u, v) ){
			e.pb({u, v});
				
			mp[{v, u}] = mp[{u, v}] = (int)e.size() - 1;
		}
	}
	
	if ( (int)e.size() != n - 1 ){
		return 0;
	}
	
	//~ for ( int i = 0; i + 1 < n; i++ ){
		//~ cout << e[i][0] << ' ' << e[i][1] << " " << i << ln;
	//~ } cout << ln;
	
	vector <vector<int>> adj(n * 2), rev(n * 2);
	
	auto add = [&](int u, int v){
		//~ cout << u << " " << v << ln;
		
		adj[u].pb(v);
		rev[v].pb(u);
	};
	
	for ( int i = 0; i < n - 1; i++ ){
		auto [u, v] = e[i];
		
		if ( x[u] == x[v] ){ // vertical
			if ( y[u] > y[v] ) swap(u, v);
			
			{ // 0
				int a = -1, b = -1;
				
				if ( id[x[u] + 2].count(y[u]) ){
					int j = id[x[u] + 2][y[u]]; a = j;
					
					if ( mp.count({u, j}) ){
						int k = mp[{u, j}];
						
						add(i, k);
					}
				}
				
				if ( id[x[u] + 2].count(y[v]) ){
					int j = id[x[u] + 2][y[v]]; b = j;
					
					if ( mp.count({j, v}) ){
						int k = mp[{j, v}];
						
						add(i, k + n);
					}
				}
				
				if ( mp.count({a, b}) ){
					add(i, mp[{a, b}]);
				}
			}
			
			{ // 1
				int a = -1, b = -1;
					
				if ( id[x[u] - 2].count(y[u]) ){
					int j = id[x[u] - 2][y[u]]; a = j;
					
					if ( mp.count({u, j}) ){
						int k = mp[{u, j}];
						
						add(i + n, k);
					}
				}
				
				if ( id[x[u] - 2].count(y[v]) ){
					int j = id[x[u] - 2][y[v]]; b = j;
					
					if ( mp.count({j, v}) ){
						int k = mp[{j, v}];
						
						add(i + n, k + n);
					}
				}
				
				if ( mp.count({a, b}) ){
					add(i + n, mp[{a, b}] + n);
				}
			}
		} else{ // horizontal
			if ( x[u] > x[v] ) swap(u, v);
			
			{ // 0
				int a = -1, b = -1;
					
				if ( id[x[u]].count(y[u] - 2) ){
					int j = id[x[u]][y[u] - 2]; a = j;
					
					if ( mp.count({u, j}) ){
						int k = mp[{u, j}];
						
						add(i, k + n);
					}
				}
				
				if ( id[x[v]].count(y[v] - 2) ){
					int j = id[x[v]][y[v] - 2]; b = j;
					
					if ( mp.count({j, v}) ){
						int k = mp[{j, v}];
						
						add(i, k);
					}
				}
				
				if ( mp.count({a, b}) ){
					add(i, mp[{a, b}]);
				}
			}
			{ // 1
				int a = -1, b = -1;
					
				if ( id[x[u]].count(y[u] + 2) ){
					int j = id[x[u]][y[u] + 2]; a = j;
					
					if ( mp.count({u, j}) ){
						int k = mp[{u, j}];
						
						add(i + n, k + n);
					}
				}
				
				if ( id[x[v]].count(y[v] + 2) ){
					int j = id[x[v]][y[v] + 2]; b = j;
					
					if ( mp.count({j, v}) ){
						int k = mp[{j, v}];
						
						add(i + n, k);
					}
				}
				
				if ( mp.count({a, b}) ){
					add(i + n, mp[{a, b}] + n);
				}
			}
		}
	}
	
	vector <int> ord, us(n * 2);
	
	auto dfs = [&](auto dfs, int u) -> void{
		if ( us[u] ) return;
		
		us[u] = true;
		
		for ( auto &v: adj[u] ){
			dfs(dfs, v);
		}
		
		ord.pb(u);
	};
	
	for ( int i = 0; i < n * 2; i++ ){
		dfs(dfs, i);
	}
	
	reverse(all(ord));
	
	vector <int> c(n * 2, -1);
	
	int ct = 0;
	
	auto trav = [&](auto trav, int u) -> void{
		if ( c[u] != -1 ) return;
		
		c[u] = ct;
		
		for ( auto &v: rev[u] ){
			trav(trav, v);
		}
	};
	
	for ( auto &u: ord ){
		if ( c[u] != -1 ) continue;
		
		trav(trav, u);
		
		ct++;
	}
	
	vector <int> t(n - 1);
	
	for ( int i = 0; i + 1 < n; i++ ){
		if ( c[i] == c[i + n] ){
			return 0;
		}
		
		t[i] = (c[i] < c[i + n]);
	}
	
	vector <int> U, V, A, B;
	
	set <pair<int,int>> st;
	
	for ( int i = 0; i + 1 < n; i++ ){
		auto [u, v] = e[i];
		
		U.pb(u), V.pb(v);
		
		if ( x[u] == x[v] ){
			if ( y[u] > y[v] ) swap(u, v);
			
			A.pb(x[u] + (t[i] ? -1 : 1));
			B.pb(y[u] + 1);
		} else{
			if ( x[u] > x[v] ) swap(u, v);
			
			A.pb(x[u] + 1);
			B.pb(y[u] + (t[i] ? 1 : -1));
		}
		
		assert(!st.count({A.back(), B.back()}));
		
		st.insert({A.back(), B.back()});
	}
	
	build(U, V, A, B);
	
	return 1;
}

• Subtask 1: 5 / 5
• Subtask 2: 10 / 10
• Subtask 3: 15 / 15
• Subtask 4: 20 / 20
• Subtask 5: 20 / 20
• Subtask 6: 0 / 30