Submission #23659

#	Time	Username	Problem	Language	Result	Execution time	Memory
23659		Hiasat	Parachute rings (IOI12_rings)	C++14	55 / 100	4040 ms	114480 KiB

rings

#include <bits/stdc++.h>

using namespace std;
int N;

int dsu[1000001], E[1000001], freq[1000001][5], sz[1000001], in[1000001], big[1000001][5], vis[1000001], vsId;

vector<int> adj[1000001];

bool block[1000001];

bool fn(int u, int p) {
	if (vis[u] == vsId) {
		return false;
	}
	if (!block[u] && in[u] > 2)
		return false;
	vis[u] = vsId;
	for (int i = 0; i < adj[u].size(); ++i) {
		int v = adj[u][i];
		if (v == p || block[v])
			continue;
		if (block[u] && vis[v] == vsId)
			continue;
		if (!fn(v, u))
			return false;
	}
	return true;
}
bool check(int u , int p) {
	block[u] = 1;
	vsId++;
	for (int i = 0; i < adj[u].size(); ++i) {
		in[adj[u][i]]--;
	}
	bool res = fn(u, p);
	for (int i = 0; i < adj[u].size(); ++i) {
		in[adj[u][i]]++;
	}
	block[u] = 0;
	return res;
}
void Init(int N_) {
	N = N_;
	for (int i = 0; i < N; ++i) {
		dsu[i] = i;
		freq[i][0] = 1;
		E[i] = 0;
		sz[i] = 1;
	}
}

int find(int u) {
	return dsu[u] == u ? u : dsu[u] = find(dsu[u]);
}

void Link(int A, int B) {
	adj[A].push_back(B);
	adj[B].push_back(A);
	freq[find(A)][in[A]]--;
	freq[find(B)][in[B]]--;
	in[A]++, in[B]++;
	in[A] = min(in[A], 4);
	in[B] = min(in[B], 4);
	freq[find(A)][in[A]]++;
	freq[find(B)][in[B]]++;
	if (find(A) != find(B)) {
		for (int i = 0 ; i <= 4  ; i++) {
			if (in[A] == i) {
				big[find(A)][i] = A;
			}
			if (in[B] == i) {
				big[find(B)][i] = B;
			}
		}
		E[find(B)] += E[find(A)];
		sz[find(B)] += sz[find(A)];
		for (int i = 0; i <= 4; ++i) {
			big[find(B)][i] = max(big[find(B)][i], big[find(A)][i]);
			freq[find(B)][i] += freq[find(A)][i];
		}
		dsu[find(A)] = find(B);
	}
	E[find(B)]++;
}

int CountCritical() {
	int res = 0;
	int wat = 0;
	int total = 0;
	bool can = true;
	for (int i = 0 ; i < N; ++i) {
		if(!can)
			break;
		if(wat > 1)
			break;
		if (find(i) == i) {
			if (freq[i][4] > 1){
				can = false;
				continue;
			}
			if (freq[i][4]) {

				if (check(big[i][4], -1)){
					res++;
				}
				if(res == 0)
					can = false;
				wat++;
			} else if (freq[i][3]) {

				if (check(big[i][3], -1)) {

					res++;
				}
				for (int j = 0 ; j < adj[big[i][3]].size(); j++) {
					int v = adj[big[i][3]][j];
					if (check(v, -1)) {
						res++;
					}
				}
				if(res == 0)
					can = false;
				wat++;
			} else {
				if(sz[i] > 0 && E[i] != sz[i]-1){
					wat++;
				}
				if(sz[i] && E[i] == sz[i])
					res = sz[find(i)];
				else if(sz[i] && E[i] == sz[i]-1){
					total += sz[find(i)];
				}else can = false;
				
			}
			
		}
	}
	if(wat == 0)
		res += total;
	if (!can || wat > 1)
		res = 0;
	return res;
}

Compilation message (stderr)

rings.cpp: In function 'bool fn(int, int)':
rings.cpp:19:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < adj[u].size(); ++i) {
                  ~~^~~~~~~~~~~~~~~
rings.cpp: In function 'bool check(int, int)':
rings.cpp:33:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < adj[u].size(); ++i) {
                  ~~^~~~~~~~~~~~~~~
rings.cpp:37:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (int i = 0; i < adj[u].size(); ++i) {
                  ~~^~~~~~~~~~~~~~~
rings.cpp: In function 'int CountCritical()':
rings.cpp:116:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int j = 0 ; j < adj[big[i][3]].size(); j++) {
                      ~~^~~~~~~~~~~~~~~~~~~~~~~

• Subtask 1: 20 / 20
• Subtask 2: 17 / 17
• Subtask 3: 18 / 18
• Subtask 4: 0 / 14
• Subtask 5: 0 / 31