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OI-codes/Luogu/P3520/P3520.cpp

92 lines
1.6 KiB
C++

#include <iostream>
#include <stack>
#include <utility>
#include <vector>
using std::cin;
using std::cout;
const char endl = '\n';
const int N = 1e5 + 5,
M = 1e6 + 5;
int n, m, d[N], root;
bool vis[N], in_stack[N], edge_used[M];
std::stack<int> st;
std::vector<std::pair<int, int>> g[N];
std::vector<std::vector<int>> ans;
void dfs(int u) {
vis[u] = true;
for (auto e : g[u]) {
int v = e.first,
id = e.second;
if (edge_used[id]) continue;
edge_used[id] = true;
dfs(v);
}
if (in_stack[u]) {
std::vector<int> res{u};
while (st.top() != u) {
res.emplace_back(st.top());
in_stack[st.top()] = false;
st.pop();
}
res.emplace_back(u);
ans.emplace_back(res);
} else {
st.push(u);
in_stack[u] = true;
}
}
int main() {
std::ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> m;
for (int i = 1, a, b, s, t; i <= m; i++) {
cin >> a >> b >> s >> t;
if (s ^ t) {
g[a].emplace_back(b, i);
g[b].emplace_back(a, i);
d[a]++, d[b]++;
}
}
for (int i = 1; i <= n; i++) {
if (d[i] % 2 != 0) {
cout << "NIE" << endl;
exit(0);
}
}
for (int i = 1; i <= n; i++) {
if (!vis[i]) dfs(i);
}
cout << ans.size() << endl;
for (auto& item : ans) {
cout << item.size() - 1 << ' ';
for (int& x : item) {
cout << x << ' ';
}
cout << endl;
}
return 0;
}