# Cod sursa(job #2663301)

Utilizator Data 25 octombrie 2020 22:57:25 Ciclu Eulerian 100 cpp-64 done Arhiva educationala 1.34 kb
``````#include <algorithm>
#include <fstream>
#include <vector>
#define SZ(x) ((int) (x).size())

using namespace std;

const int NMAX = 100005, MMAX = 500005;

ifstream cin("ciclueuler.in");
ofstream cout("ciclueuler.out");

vector<int> G[NMAX];
vector<int> ans;
vector<int> stk;

bool usedEdge[MMAX];
int from[MMAX], to[MMAX], n, m;

void citire()
{
int x, y;
cin >> n >> m;

for (int i = 1; i <= m; ++i)
cin >> x >> y,
G[x].push_back(i),
G[y].push_back(i),
from[i] = x, to[i] = y;
}

int main()
{
citire();
for (int i = 1; i <= n; ++i)
{
if (SZ(G[i]) & 1)
{
cout << "-1\n";
return 0;
}
}

int tor;
stk.push_back(1);
while (!stk.empty())
{
int node = stk.back();
if (!G[node].empty())
{
int e = G[node].back();
G[node].pop_back();
if (!usedEdge[e])

usedEdge[e] = true,
tor = from[e] ^ to[e] ^ node,
stk.push_back(tor);

}
else
stk.pop_back(),
ans.push_back(node);

}

for (int i = 0; i < ans.size() - 1; ++i)
cout << ans[i] << ' ';
cout << '\n';

cin.close();
cout.close();

return 0;
}
``````