This submission is migrated from previous version of oj.uz, which used different machine for grading. This submission may have different result if resubmitted.
#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
//#pragma GCC optimize("unroll-loops")
//#pragma GCC optimize("-O3")
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("fast-math")
//#pragma GCC optimize("no-stack-protector")
#define F first
#define S second
#define sz(x) int(x.size())
#define pb push_back
#define N 100005
#define MOD ll(1e9 + 7)
#define block 500
using namespace std;
//using namespace __gnu_pbds;
typedef long double ld;
typedef long long ll;
typedef short int si;
//typedef tree <int, null_type, less_equal<int>, rb_tree_tag, tree_order_statistics_node_update> ordered_set;
int pr[N], rk[N], a[N], b[N], c[N], basis[32], id[32], conv[32], sz, cnt[N];
vector <int> ans[32];
vector <pair <int, int> > g[N], vr;
void make(int x) {pr[x] = x; rk[x] = 1;}
vector <int> check;
int fnd(int x) {if (pr[x] != x) pr[x] = fnd(pr[x]); return pr[x];}
void link(int x, int y)
{
if (rk[y] > rk[x]) swap(x, y);
pr[y] = x;
rk[x] += rk[y];
}
void dfs(int v, int p)
{
for (auto it : g[v])
{
if (it.F == p) continue;
cnt[it.F] = cnt[v] ^ it.S;
dfs(it.F, v);
}
}
void add_basis(int x)
{
for (int i = 0; i < 32; i++)
if ((1 << i) & x)
{
if (!basis[i])
{
basis[i] = x;
id[i] = sz;
conv[sz] = i;
sz++;
return;
}
x ^= basis[i];
}
}
void add(pair <int, int> x)
{
for (int i = 0; i < 32; i++)
if ((1 << i) & x.S)
{
ans[id[i]].pb(x.F);
x.S ^= basis[i];
}
}
int main()
{
//freopen("input.txt", "r", stdin); freopen("output.txt", "w", stdout);
ios_base::sync_with_stdio(0); istream::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int n, m;
cin >> n >> m;
for (int i = 1; i <= n; i++) make(i);
for (int i = 1; i <= m; i++)
{
cin >> a[i] >> b[i] >> c[i];
int x = fnd(a[i]), y = fnd(b[i]);
if (x != y)
{
link(x, y);
g[a[i]].pb({b[i], c[i]});
g[b[i]].pb({a[i], c[i]});
} else check.pb(i);
}
dfs(1, -1);
for (auto it : check)
{
int t = cnt[a[it]] ^ cnt[b[it]] ^ c[it];
if (!t) continue;
vr.pb({it, t});
add_basis(t);
}
if (!sz(vr)) {cout << 0 << endl; exit(0);}
cout << sz << endl;
for (auto it : vr) add(it);
for (int i = 0; i < sz; i++)
{
cout << basis[conv[i]] << " " << sz(ans[i]) << " ";
sort(ans[i].begin(), ans[i].end());
for (auto it : ans[i]) cout << it << " ";
cout << endl;
}
}
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