Submission #736383

#	Time	Username	Problem	Language	Result	Execution time	Memory
736383		jk410	Thousands Islands (IOI22_islands)	C++17	12.35 / 100	39 ms	7016 KiB

islands

#include "islands.h"
#include <bits/stdc++.h>
using namespace std;
int n;
int edge[1000][1000];
int deg[1000];
int par[1000];
bool visited[1000];
void dfs(int v) {
	visited[v] = true;
	for (int i = 0; i < n; i++) {
		if (edge[v][i] != -1 && !visited[i]) {
			par[i] = v;
			dfs(i);
		}
	}
}
pair<int,int> f(int v) {
	pair<int, int> ret = { -1,-1 };
	for (int i = 0; i < n; i++) {
		if (edge[v][i] != -1) {
			if (ret.first == -1)
				ret.first = i;
			else if (ret.second == -1)
				ret.second = i;
		}
	}
	return ret;
}
variant<bool, vector<int>> find_journey(int _n, int m, vector<int> u, vector<int> v) {
	n = _n;
	memset(edge, -1, sizeof(edge));
	memset(par, -1, sizeof(par));
	for (int i = 0; i < m; i++) {
		edge[u[i]][v[i]] = i;
		deg[u[i]]++;
	}
	visited[0] = true;
	dfs(0);
	int x = -1;
	for (int i = 0; i < n; i++) {
		if (visited[i] && deg[i] > 2)
			x = i;
	}
	if (deg[0] > 1)
		x = 0;
	if (x == -1)
		return false;
	vector<int> p;
	for (int i = x;; i = par[i]) {
		p.push_back(i);
		if (!i)
			break;
	}
	vector<int> ret;
	for (int i = (int)p.size() - 1; i; i--)
		ret.push_back(edge[p[i]][p[i - 1]]);
	pair<int, int> tmp = f(x);
	ret.push_back(edge[x][tmp.first]);
	ret.push_back(edge[tmp.first][x]);
	ret.push_back(edge[x][tmp.second]);
	ret.push_back(edge[tmp.second][x]);
	ret.push_back(edge[tmp.first][x]);
	ret.push_back(edge[x][tmp.first]);
	ret.push_back(edge[tmp.second][x]);
	ret.push_back(edge[x][tmp.second]);
	for (int i = 1; i < (int)p.size(); i++)
		ret.push_back(edge[p[i]][p[i - 1]]);
	return ret;
}

• Subtask 1: 0 / 5
• Subtask 2: 5 / 5
• Subtask 3: 7.35 / 21
• Subtask 4: 0 / 24
• Subtask 5: 0 / 45