HDU 3715 2-sat

/****************************************************************************************************
    二分+2-sat，二分程序能到达的最远步骤，尼玛二分写错了吃了一次WA。。。
****************************************************************************************************/
#include <iostream>
#include <functional>
#include <algorithm>
//#include <hash_map>		//Visual C++ lib
#include <complex>
#include <cstdlib>
#include <cstring>
#include <fstream>
#include <sstream>
#include <utility>
#include <bitset>
#include <cctype>
#include <cstdio>
#include <limits>
#include <memory>
#include <string>
#include <vector>
#include <cmath>
#include <ctime>
#include <queue>
#include <stack>
#include <list>
#include <map>
#include <set>
using namespace std;

#define LOWBIT(x) ( (x) & ( (x) ^ ( (x) - 1 ) ) )
#define CLR(x, k) memset((x), (k), sizeof(x))
#define CPY(t, s) memcpy((t), (s), sizeof(s))
#define SC(t, s) static_cast<t>(s)
#define LEN(s) static_cast<int>( strlen((s)) )
#define SZ(s) static_cast<int>( (s).size() )

typedef double LF;
//typedef long long LL;		//GNU C++
//typedef unsigned long long ULL;
typedef __int64 LL;		//Visual C++ 2010
typedef unsigned __int64 ULL;

typedef pair<int, int> PII;
typedef pair<LL, LL> PLL;
typedef pair<double, double> PDD;

//typedef hash_map<int, int>::iterator HMI;
typedef map<int, int>::iterator MI;
typedef vector<int>::iterator VI;
typedef list<int>::iterator LI;
typedef set<int>::iterator SI;

template <typename T>
T sqa(const T &x)
{
	return x * x;
}

const int INF_INT = 0x3f3f3f3f;
const LL INF_LL = 0x7fffffffffffffffLL;		//15f
const double oo = 10e9;
const double eps = 10e-9;
const double PI = acos(-1.0);

const int MAXN = 204;
const int MAXV = MAXN << 1;
const int MAXE = MAXV * MAXV;

struct Edges
{
	int end;
	int rk;
	int next;
}edges[MAXE];
int ecnt, head[MAXV];
int test, n, m;
int id[MAXV], pre[MAXV], low[MAXV], S[MAXV], stop, cnt, scnt;

void inline add_edge(int u, int v, int r)
{
	edges[ecnt].end = v;
	edges[ecnt].rk = r;
	edges[ecnt].next = head[u];
	head[u] = ecnt++;
	return ;
}
void tarjan(int u, int n, int key)
{
	int t, minc = low[u] = pre[u] = cnt++;
	S[stop++] = u;
	for (int i = head[u]; i != -1; i = edges[i].next)
	{
		if (edges[i].rk > key)
		{
			continue ;
		}
		int v = edges[i].end;
		if (-1 == pre[v])
		{
			tarjan(v, n, key);
		}
		minc = min(minc, low[v]);
	}
	if (minc < low[u])
	{
		low[u] = minc;
		return ;
	}
	do
	{
		id[ t = S[--stop] ] = scnt;
		low[t] = n;
	}
	while (t != u);
	++scnt;
	return ;
}
bool _2sat(int key)
{
	stop = cnt = scnt = 0;
	CLR(pre, -1);
	n <<= 1;
	for (int i = 0; i < n; ++i)
	{
		if (-1 == pre[i])
		{
			tarjan(i, n, key);
		}
	}
	n >>= 1;
	for (int i = 0; i < n; ++i)
	{
		if (id[i] == id[i + n])
		{
			return false;
		}
	}
	return true;
}
int bisearch()
{
	int l = 0, r = m - 1, mid = (l + r) / 2, res = (l + r) / 2;
	while (l <= r)
	{
		mid = (l + r) / 2;
		if (_2sat(mid))
		{
			res = mid;
			l = mid + 1;
		}
		else
		{
			r = mid - 1;
		}
	}
	return res;
}
void ace()
{
	int a, b, c;
	for (scanf("%d", &test); test--; )
	{
		scanf("%d %d", &n, &m);
		ecnt = 0;
		CLR(head, -1);
		for (int i = 0; i < m; ++i)
		{
			scanf("%d %d %d", &a, &b, &c);
			if (2 == c)
			{
				add_edge(a, b + n, i);
				add_edge(b, a + n, i);
			}
			else if (1 == c)
			{
				add_edge(a, b, i);
				add_edge(b, a, i);
				add_edge(a + n, b + n, i);
				add_edge(b + n, a + n, i);
			}
			else
			{
				add_edge(a + n, b, i);
				add_edge(b + n, a, i);
			}
		}
		printf("%d\n", bisearch() + 1);
	}
	return ;
}
int main()
{
	ace();
	return 0;
}