Submission #617783

#	Time	Username	Problem	Language	Result	Execution time	Memory
617783		amunduzbaev	Fountain Parks (IOI21_parks)	C++17	5 / 100	298 ms	20816 KiB

parks

#include "parks.h"

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

#ifndef EVAL
#include "grader.cpp"
#endif

#define ar array
typedef long long ll;

int construct_roads(vector<int> x, vector<int> y) {
	int n = x.size();
	
	map<ar<int, 2>, int> mm;
	for(int i=0;i<n;i++){
		swap(x[i], y[i]);
		mm[{x[i], y[i]}] = i;
	}
	
	vector<ar<int, 2>> e, p;
	vector<int> par(n), sz(n, 1);
	iota(par.begin(), par.end(), 0);
	function<int(int)> f = [&](int x) { return (par[x] == x ? x : par[x] = f(par[x])); };
	auto merge = [&](int a, int b){
		a = f(a), b = f(b);
		if(a == b) return false;
		if(sz[a] < sz[b]) swap(a, b);
		par[b] = a, sz[a] += sz[b];
		return true;
	};
	
	for(int i=0;i<n;i++){
		if(mm.count({x[i], y[i] - 2})){
			int j = mm[{x[i], y[i] - 2}];
			if(merge(i, j)){
				e.push_back({j, i});
				p.push_back({-1, -1});
			}
		}
	}
	
	for(int i=0;i<n;i++){
		if(y[i] == 2 || y[i] == 6){
			if(mm.count({x[i] - 2, y[i]})){
				int j = mm[{x[i] - 2, y[i]}];
				if(merge(i, j)){
					e.push_back({j, i});
					p.push_back({x[i] - 1, y[i] + (x[i] == 2 ? -1 : +1)});
				}
			}
		}
	}
	
	for(int i=0;i<n;i++){
		if(y[i] == 4){
			if(mm.count({x[i] - 2, y[i]})){
				int j = mm[{x[i] - 2, y[i]}];
				if(merge(i, j)){
					e.push_back({j, i});
					p.push_back({-1, -1});
				}
			}
		}
	}
	
	if(sz[f(0)] != n) return 0;
	assert((int)e.size() == n - 1);
	par.pop_back();
	iota(par.begin(), par.end(), 0);
	sort(par.begin(), par.end(), [&](int i, int j){
		if(x[e[i][0]] != x[e[j][0]]){
			return x[e[i][0]] < x[e[j][0]];
		} else {
			int a = (x[e[i][0]] != x[e[i][1]]), b = (x[e[j][0]] != x[e[j][1]]);
			return a < b;
		}
	});
	
	mm.clear();
	for(auto i : par){
		if(~p[i][0]) continue;
		//~ cout<<e[i][0]<<" "<<e[i][1]<<"\n";
		if(x[e[i][0]] == x[e[i][1]]){
			int Y = (y[e[i][0]] + y[e[i][1]]) / 2;
			p[i] = {x[e[i][0]] - 1, Y};
			if(mm.count(p[i])){
				p[i][0] += 2;
				assert(!mm.count(p[i]));
			}
			mm[p[i]] = 1;
		} else {
			int X = (x[e[i][0]] + x[e[i][1]]) / 2;
			p[i] = {X, y[e[i][0]] + 1};
			if(mm.count(p[i])){
				p[i][1] -= 2;
				assert(!mm.count(p[i]));
			}
			
			mm[p[i]] = 1;
		}
	}
	
	mm.clear();
	vector<int> u(n - 1), v(n - 1), A(n - 1), B(n - 1);
	for(int i=0;i+1<n;i++){
		u[i] = e[i][0], v[i] = e[i][1], A[i] = p[i][0], B[i] = p[i][1];
		swap(A[i], B[i]);
		assert(!mm.count(p[i]));
		mm[p[i]];
	}
	
	build(u, v, A, B);
	return 1;
}

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