Monotonic

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef __int128 lll;

constexpr int N = 1000;
constexpr int M = 15;

mt19937 rnd;

typedef pair<int, int> op;

template<typename T>
void exec(vector<T> &v, vector<op> ops) {
	for (auto o : ops) {
		if (v[o.first] > v[o.second]) {
			swap(v[o.first], v[o.second]);
		}
	}
}

template<typename T>
bool isOrder(const vector<T> &v) {
	for(size_t i = 1; i < v.size(); i++) {
		if (!(v[i-1] < v[i])) return false;
	}
	return true;
}

inline bool ready(vector<int> &v, int n) {
	int mask = (1 << (n)) - 1;
	for (int a : v) {
		if ((a & mask) != mask) return false;
	}
	return true;
}

void test() {
	int n, m;
	cin >> n >> m;
	vector<int> v(n);
	vector<op> ops(m);
	for (auto &o : ops) {
		cin >> o.first >> o.second;
		o.first--;
		o.second--;
	}
	
	// Init v
	for (int i = 0; i < n; i++) {
		v[i] = 1<<i;
	}
	
	// Iterate until ready
	int k = 0;
	while (!ready(v, n) && k++ < 16) {
		for (auto o : ops) {
			v[o.first] = v[o.second] = v[o.first] | v[o.second];
		}
	}
	if (!ready(v, n)) {
		cout << "-1\n";
	} else {
		cout << k << "\n";
	}
}

int main(){
	int t;
	cin>>t;
	while(t--)test();
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: WRONG ANSWER

Test 3

Verdict: WRONG ANSWER

Test 4

Verdict: ACCEPTED

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: WRONG ANSWER

Test 7

Verdict: WRONG ANSWER

Test 8

Verdict: WRONG ANSWER

Test 9

Verdict: WRONG ANSWER

Test 10

Verdict: ACCEPTED