Submission #786352

#	Time	Username	Problem	Language	Result	Execution time	Memory
786352		khshg	Thousands Islands (IOI22_islands)	C++17	0 / 100	61 ms	10628 KiB

islands

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

variant<bool, vector<int>> find_journey(int N, int M, vector<int> U, vector<int> V) {
	vector<map<int, vector<int>>> adj(N);
	vector<int> out(N);
	for(int i = 0; i < M; ++i) {
		adj[U[i]][V[i]].push_back(i);
		++out[U[i]];
	}
	int cur = 0, prev = -1;
	vector<int> way, ans;
	while(1) {
		int cs = out[cur] - (prev != -1);
		if(cs == 0) return false;
		if(cs == 1) for(auto& u : adj[cur]) if(u.first != prev) { way.push_back(u.second[0]); prev = cur; cur = u.first; continue; }
		break;
	}
	ans = way;
	vector<int> z;
	for(auto& u : adj[cur]) if(u.first != prev) {
		for(auto& v : u.second) {
			z.push_back(v);
			if((int)z.size() == 2) break;
		}
		if((int)z.size() == 2) break;
	}
	ans.push_back(z[0]);
	ans.push_back(z[0] / 2 * 2 + 1 - z[0]);
	ans.push_back(z[1]);
	ans.push_back(z[1] / 2 * 2 + 1 - z[1]);
	ans.push_back(z[0] / 2 * 2 + 1 - z[0]);
	ans.push_back(z[0]);
	ans.push_back(z[1] / 2 * 2 + 1 - z[1]);
	ans.push_back(z[1]);
	reverse(begin(way), end(way));
	for(auto& u : way) ans.push_back(u);
	return ans;
}

• Subtask 1: 0 / 5
• Subtask 2: 0 / 5
• Subtask 3: 0 / 21
• Subtask 4: 0 / 24
• Subtask 5: 0 / 45