Submission #54766

#	Time	Username	Problem	Language	Result	Execution time	Memory
54766		ksun48	Park (JOI17_park)	C++14	20 / 100	1343 ms	980 KiB

park

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

int P[1400];
int ask(int a, int b){
	if(P[a] == 0 || P[b] == 0) return 0;
	if(a == b) return 1;
	return Ask(min(a,b), max(a,b), P);
}

void found(int a, int b){
	Answer(min(a,b), max(a,b));
}

void solve1(int n){
	for(int i = 0; i < n; i++){
		P[i] = 0;
	}
	for(int i = 0; i < n; i++){
		for(int j = i+1; j < n; j++){
			P[i] = P[j] = 1;
			if(ask(i,j)){
				found(i,j);
			}
			P[i] = P[j] = 0;
		}
	}
}

int check_edge(int a, int b, int n){
	if(a == b) return 0;
	for(int i = 0; i < n; i++){
		P[i] = 0;
	}
	P[a] = P[b] = 1;
	return ask(a, b);
}

int check_subtree(int a, int b, int c, int n){
	// a-b is an edge, check if x == b or x is in b's side
	for(int i = 0; i < n; i++){
		P[i] = 1;
	}
	P[b] = 0;
	if(ask(a,c)){
		return 0;
	}
	return 1;
}

void solvetreev(vector<int> v, int n){
	if(v.size() <= 1) return;
	int a;
	while(1){
		a = v[rand() % v.size()];
		int numdiff = 0;

		// 9 trials
		for(int q = 0; q < 2; q++){
			int b = v[rand() % v.size()];
			int c = v[rand() % v.size()];
			if(check_subtree(b, a, c, n)){
				numdiff++;
			}
		}
		if(numdiff >= 2){
			break;
		}
	}
	vector<pair<int, vector<int> > > children;
	for(int x : v){
		if(check_edge(a, x, n)){
			found(a,x);
			children.push_back({x, vector<int>()});
		}
	}
	for(int x : v){
		if(x == a) continue;
		/*while(1){
			int did = 0;
			for(int i = 0; i + 1 < children.size(); i++){
				if(children[i+1].second.size() > children[i].second.size()){
					swap(children[i], children[i+1]);
					did = 1;
				}
			}
			if(!did) break;
		}*/
		random_shuffle(children.begin(), children.end());
		for(int i = 0; i < children.size(); i++){
			if(check_subtree(a, children[i].first, x, n)){
				children[i].second.push_back(x);
				break;
			}
		}
	}
	for(int i = 0; i < children.size(); i++){
		solvetreev(children[i].second, n);
	}
	return;
}

void solve2(int n){
	vector<int> v;
	for(int i = 0; i < n; i++){
		v.push_back(i);
	}
	solvetreev(v, n);
}
void Detect(int T, int N) {
	srand(48);
	if(T == 1){
		solve1(N);
	} else if(T >= 2){
		solve2(N);
	}
}

Compilation message (stderr)

park.cpp: In function 'void solvetreev(std::vector<int>, int)':
park.cpp:91:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i = 0; i < children.size(); i++){
                  ~~^~~~~~~~~~~~~~~~~
park.cpp:98:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int i = 0; i < children.size(); i++){
                 ~~^~~~~~~~~~~~~~~~~

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 0 / 27
• Subtask 4: 0 / 30
• Subtask 5: 0 / 23