Submission #1046608

#	Time	Username	Problem	Language	Result	Execution time	Memory
1046608		Unforgettablepl	Fountain Parks (IOI21_parks)	C++17	45 / 100	909 ms	108740 KiB

parks

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

int construct_roads(vector<int> x,vector<int> y){
	int n = x.size();
	map<pair<int,int>,int> lookup;
	for(int i=0;i<n;i++)lookup[{x[i],y[i]}]=i;
	vector<int> u,v,a,b;
	vector<vector<int>> adj(1);
	vector<vector<int>> adjsepar(n);
	vector<tuple<int,int,int,int>> edges;
	edges.emplace_back(0,0,0,0);
	int S = 0;
	for(int i=0;i<n;i++){
		if(lookup.count({x[i]+2,y[i]})){
			adjsepar[i].emplace_back(lookup[{x[i]+2,y[i]}]);
			adjsepar[lookup[{x[i]+2,y[i]}]].emplace_back(i);
			S++;
			adj.emplace_back();
			edges.emplace_back(i,lookup[{x[i]+2,y[i]}],x[i]+1,y[i]-1);
			if(lookup.count({x[i]+1,y[i]-1})){
				adj[S].emplace_back(lookup[{x[i]+1,y[i]-1}]);
				adj[lookup[{x[i]+1,y[i]-1}]].emplace_back(S);
			} else lookup[{x[i]+1,y[i]-1}]=S;
			S++;
			adj.emplace_back();
			edges.emplace_back(i,lookup[{x[i]+2,y[i]}],x[i]+1,y[i]+1);
			if(lookup.count({x[i]+1,y[i]+1})){
				adj[S].emplace_back(lookup[{x[i]+1,y[i]+1}]);
				adj[lookup[{x[i]+1,y[i]+1}]].emplace_back(S);
			} else lookup[{x[i]+1,y[i]+1}]=S;
			adj[S].emplace_back(S-1);
			adj[S-1].emplace_back(S);
		}
		if(lookup.count({x[i],y[i]-2})){
			adjsepar[i].emplace_back(lookup[{x[i],y[i]-2}]);
			adjsepar[lookup[{x[i],y[i]-2}]].emplace_back(i);
			S++;
			adj.emplace_back();
			edges.emplace_back(i,lookup[{x[i],y[i]-2}],x[i]-1,y[i]-1);
			if(lookup.count({x[i]-1,y[i]-1})){
				adj[S].emplace_back(lookup[{x[i]-1,y[i]-1}]);
				adj[lookup[{x[i]-1,y[i]-1}]].emplace_back(S);
			} else lookup[{x[i]-1,y[i]-1}]=S;
			S++;
			adj.emplace_back();
			edges.emplace_back(i,lookup[{x[i],y[i]-2}],x[i]+1,y[i]-1);
			if(lookup.count({x[i]+1,y[i]-1})){
				adj[S].emplace_back(lookup[{x[i]+1,y[i]-1}]);
				adj[lookup[{x[i]+1,y[i]-1}]].emplace_back(S);
			} else lookup[{x[i]+1,y[i]-1}]=S;
			adj[S].emplace_back(S-1);
			adj[S-1].emplace_back(S);
		}
	}
	vector<bool> visited(n);
	int vis = 0;
	function<void(int)> dfshelp = [&](int x){
		if(visited[x])return;
		visited[x]=true;
		vis++;
		for(int&i:adjsepar[x])dfshelp(i);
	};
	dfshelp(0);
	vector<int> colour(S+1,-1);
	bool works = true;
	function<void(int,int)> dfs = [&](int x,int col){
		if(colour[x]!=-1){
			if(colour[x]!=col)works=false;
			return;
		}
		colour[x]=col;
		for(int&i:adj[x])dfs(i,col^1);
	};
	for(int i=1;i<=S;i++)if(colour[i]==-1)dfs(i,0);
	if(!works or vis!=n)return 0;
	for(int i=1;i<=S;i++){
		if(colour[i]==0)continue;
		auto [c,d,e,f] = edges[i];
		u.emplace_back(c);
		v.emplace_back(d);
		a.emplace_back(e);
		b.emplace_back(f);
	}
	build(u,v,a,b);
	return 1;
}

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