CF 1385E

#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <set>
#include <queue>
#include <map>
#include <sstream>
#include <cstdio>
#include <cstring>
#include <numeric>
#include <cmath>
#include <iomanip>
#include <deque>
#include <bitset>
#include <cassert>
//#include <unordered_set>
#include <unordered_map>
#define ll              long long
#define pii             pair<int, int>
#define PLL             pair<ll,ll>                 
#define rep(i,a,b)      for(int  i=a;i<=b;i++)
#define dec(i,a,b)      for(int  i=a;i>=b;i--)
#define forn(i, n)      for(int i = 0; i < int(n); i++)
using namespace std;
int dir[4][2] = { { 1,0 },{ 0,1 } ,{ 0,-1 },{ -1,0 } };
const long long INF = 0x7f7f7f7f7f7f7f7f;
const int inf = 0x3f3f3f3f;
const double pi = acos(-1.0);
const double eps = 1e-6;
const ll mod = 1e9 + 7;

inline ll read()
{
    ll x = 0; bool f = true; char c = getchar();
    while (c < '0' || c > '9') { if (c == '-') f = false; c = getchar(); }
    while (c >= '0' && c <= '9') x = (x << 1) + (x << 3) + (c ^ 48), c = getchar();
    return f ? x : -x;
}

ll gcd(ll m, ll n)
{
    return n == 0 ? m : gcd(n, m % n);
}
ll qpow(ll m, ll k)
{
    ll res = 1, t = m;
    while (k)
    {
        if (k & 1)
            res = res * t % mod;
        t = t * t % mod;
        k >>= 1;
    }
    return res;
}
/**********************************************************/

const int N = 1e6 + 5;

vector<int>::iterator it;
vector<vector<int>> g;
vector<int> in,order;
int n, m, num;

void topsort()
{
    queue<int> q;
    rep(i, 1, n)
    {
        if (!in[i])
            q.push(i);
    }
    while (!q.empty())
    {
        int f = q.front();
        q.pop();
        num++;
        order[f] = num;
        for (auto to : g[f])
        {
            in[to]--;
            if (!in[to])
                q.push(to);
        }
    }
}

int main()
{
#ifdef _DEBUG
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
#endif
    int T;
    cin >> T;
    while (T--)
    {
        cin >> n >> m;

        g = vector<vector<int>>(n + 1);
        vector<int> u(m + 1), v(m + 1);
        in = vector<int>(n + 1);
        order = vector<int>(n + 1);
        num = 0;

        rep(i, 1, m)
        {
            int t;
            cin >> t >> u[i] >> v[i];
            if (t)
                g[u[i]].push_back(v[i]),in[v[i]]++;
        }
        topsort();
        if (num != n)
            cout << "NO" << endl;
        else
        {
            cout << "YES" << endl;
            rep(i, 1, m)
            {
                if (order[u[i]] < order[v[i]])
                    cout << u[i] << " " << v[i] << endl;
                else
                    cout << v[i] << " " << u[i] << endl;
            }
        }
    }
}

CF 1385E

拓扑序小的往拓扑序大的加边不会形成环