使用到的数据结构：

struct eage {ll u,v,w;};//存储起点，重点，边权de数据类型
eage e[N];//开数组
ll m;//一共m条边
bool vis[N];//防止死循环，在dfs之前判断一下有没有走过

#include <bits/stdc++.h>using namespace std;
typedef long long ll;
typedef double db;
typedef long double ldb;
typedef pair<int, int> pii;
typedef pair<ll, ll> PII;
#define pb emplace_back
//#define int ll
#define all(a) a.begin(),a.end()
#define x first
#define y second
#define ps push_back
#define endl '\n'
#define IOS ios::sync_with_stdio(0),cin.tie(0),cout.tie(0)void solve();const int N = 1e6 + 10;signed main() {IOS;solve();return 0;
}struct eage {ll u,v,w;};
eage e[N];
ll idx,m;
bool vis[N];void dfs(ll u)
{vis[u] = 1;for(int i = 1; i <= m; ++ i){if(e[i].u == u){ll v = e[i].v, w = e[i].w;cout << u << ' ' << v << ' ' << w << endl;if(vis[v]) continue;dfs(v);}}
}void solve() {ll n;cin >> n >> m;for(int i = 1; i <= m; ++ i){ll u,v,w;cin >> u >> v >> w ;e[i] = {u,v,w};}dfs(1);
}