Submission #1053297

#	Time	Username	Problem	Language	Result	Execution time	Memory
1053297		dozer	Fountain Parks (IOI21_parks)	C++17	70 / 100	992 ms	143120 KiB

parks

#include "parks.h"
#include <bits/stdc++.h>
using namespace std;
#define sp " "
#define endl "\n"
#define fileio() freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout)
#define pb push_back
#define pii pair<int, int>
#define fastio() cin.tie(0), ios_base::sync_with_stdio(0)
#define st first
#define nd second
#define ll long long
#define LL node * 2
#define RR node * 2 + 1
#define N 300005


const int modulo = 1e9 + 7;
const ll INF = 2e18 + 7;


int par[N], sz[N], TOT;
pii rev[N];

int find(int node){
	if (par[node] == node) return node;
	return par[node] = find(par[node]);
}


void uni(int a, int b){
	a = find(a), b = find(b);
	if (a == b) return;
	TOT--;
	if (sz[a] < sz[b]) swap(a, b);
	par[b] = a;
	sz[a] += b;
}


int construct_roads(vector<int> x, vector<int> y) {
    if (x.size() == 1) {
		build({}, {}, {}, {});
	    return 1;
    }
    map<pii ,int> ind;
    int n = x.size();
    vector<array<int, 3>> srt;
    for (int i = 0; i < n; i++) srt.pb({x[i], y[i], i});
    sort(srt.begin(), srt.end());
	for (int i = 0; i < n; i++) x[i] = srt[i][0], y[i] = srt[i][1];
    for (int i = 0; i < n; i++){
    	ind[{x[i], y[i]}] = i;
    	sz[i] = 1, par[i] = i;
    }

    vector<pii> dir = {{0, -2}, {-2, 0}, {0, 2}, {2, 0}};

    vector<pii> edges, b1, b2;
    map<pii, int> cnt;
    map<pii, set<int>> rev2;

    int cntr = 0;
    for (auto k : dir){
	    for (int i = 0; i < n; i++){
	    	int a = x[i], b = y[i];
    		int c = a + k.st, d = b + k.nd;
    		if (ind.count({c, d}) && ind[{c, d}] > i){
    			int g = (a + c) / 2, h = (b + d) / 2;
    			pii f1, f2;
    			if (b == d){
    				f1 = {g, h + 1};
    				f2 = {g, h - 1};
    			}
    			else{
    				f1 = {g + 1, h};
    				f2 = {g - 1, h};
    			}
    			edges.pb({i, ind[{c, d}]});
    			b1.pb(f1);
    			b2.pb(f2);
    			rev2[f1].insert(cntr);
    			rev2[f2].insert(cntr);
    			cnt[f1]++;
    			cnt[f2]++;
    			cntr++;
    		}
    	}
    }

    queue<int> q;
    for (int i = 0; i < cntr; i++){
    	if (cnt[b1[i]] == 1 || cnt[b2[i]] == 1) q.push(i);
    }

 	vector<int> u, v, a, b;
    
    set<int> undone;

    for (int i = 0; i < cntr; i++) undone.insert(i);
    TOT = n;
	while(TOT > 1){
		 while(!q.empty()){
	    	int top = q.front();
	    	q.pop();
	    	
	    	if (undone.count(top) == 0) continue;
	    	
	    	pii todo = {-1, -1};
	    	if (cnt[b1[top]] == 1) todo = b1[top];
	    	else if (cnt[b2[top]] == 1) todo = b2[top];
	    	if (todo.st == -1) continue;

	    	a.pb(todo.st), b.pb(todo.nd);
	    	vector<pii> V = {b1[top], b2[top]};
	    	for (auto i : V){
	    		cnt[i]--;
	    		rev2[i].erase(top);
	    		if (rev2[i].size()){
	    			q.push(*rev2[i].begin());
	    		}
	    	}

	    	u.pb(srt[edges[top].st][2]);
	    	v.pb(srt[edges[top].nd][2]);
	    	uni(edges[top].st, edges[top].nd);
	    	undone.erase(top);
	    }	

	    if (TOT == 1) break;

	    auto it = undone.begin();
	    while(it != undone.end()){
	    	int i = *it;
	    	if (find(edges[i].st) == find(edges[i].nd)) it = undone.erase(it); 
	    	else if (cnt[b1[i]] == 0 && cnt[b2[i]] == 0) it = undone.erase(it);
	    	else break;
	    }

	    if (undone.empty()) break;
		int tmp = *undone.begin();
		cnt[b1[tmp]] = 1;
		q.push(tmp);
	}

	
	if (TOT == 1){
		build(u, v, a, b);
		return 1;
	}
   
   return 0;
}
/*

static void check(bool cond, string message) {
	if (!cond) {
		printf("%s\n", message.c_str());
		fclose(stdout);
		exit(0);
	}
}

static int n;
static bool build_called;
static int m;
static vector<int> _u, _v, _a, _b;

void build(vector<int> u, vector<int> v, vector<int> a, vector<int> b) {
	check(!build_called, "build is called more than once");
	build_called = true;
	m = u.size();
	check(int(v.size()) == m, "u.size() != v.size()");
	check(int(a.size()) == m, "u.size() != a.size()");
	check(int(b.size()) == m, "u.size() != b.size()");
	_u = u;
	_v = v;
	_a = a;
	_b = b;
}

int main() {
	fileio();
	assert(scanf("%d", &n) == 1);
	vector<int> x(n), y(n);
	for (int i = 0; i < n; i++) {
		assert(scanf("%d%d", &x[i], &y[i]) == 2);
	}
	fclose(stdin);

	build_called = false;
	const int possible = construct_roads(x, y);

	check(possible == 0 || possible == 1, "Invalid return value of construct_roads()");
	if (possible == 1) {
		check(build_called, "construct_roads() returned 1 without calling build()");
	} else {
		check(!build_called, "construct_roads() called build() but returned 0");
	}

	printf("%d\n", possible);
	if (possible == 1) {
		printf("%d\n", m);
		for (int j = 0; j < m; j++) {
			printf("%d %d %d %d\n", _u[j], _v[j], _a[j], _b[j]);
		}
	}
	fclose(stdout);
	return 0;
}
*/

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