Tunnelit

input/code.cpp: In function 'int main()':
input/code.cpp:35:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for(int i = 0; i < r[d].size(); i++) if(r[d][i] == c) e = i;
                                 ^
input/code.cpp:31:12: warning: 'c' may be used uninitialized in this function [-Wmaybe-uninitialized]
   while(r[c].size() > 0) c = r[c][0];
            ^

#include <bits/stdc++.h>

using namespace std;
typedef long long ll;

vector<vector<int>> v, r;
vector<bool> z;
int s = 0;

int main() {
	cin.tie(0);
	ios_base::sync_with_stdio(false);
	
	int n, m, a, b;
	cin >> n >> m;	
	
	v.resize(n);
	r.resize(n);
	z.resize(n);
	
	for(int i = 0; i < m; i++) {
		cin >> a >> b;
		v[a-1].push_back(b-1);
		r[b-1].push_back(a-1);
	}
	
	int c;
	
	while(m > 0) {
		for(int i = 0; i < n; i++) if(v[i].size() > 0) c = i;
		while(r[c].size() > 0) c = r[c][0];
		while(v[c].size() > 0) {
			int d = v[c].back(), e = 0;
			v[c].pop_back();
			for(int i = 0; i < r[d].size(); i++) if(r[d][i] == c) e = i;
			r[d].erase(r[d].begin() + e);
			c = d;
			m--;
		}
		s++;
	}
	
	cout << s << endl;
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 12

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 13

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 14

Group: 3

Verdict: TIME LIMIT EXCEEDED

Test 15

Group: 3

Verdict: TIME LIMIT EXCEEDED