Tunnels

input/code.cpp: In function 'int main()':
input/code.cpp:29:70: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         if (nextEdge[noIngoing.front()] == e[noIngoing.front()].size()) {
                                                                      ^
input/code.cpp:36:52: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         while (nextEdge[current] < e[current].size()) {
                                                    ^

#include <iostream>
#include <vector>
#include <queue>

using namespace std;

int n, m;
vector<int> e[100000];
int nextEdge[100000];
int ingoing[100000];

int main() {
    cin >> n >> m;
    for (int i = 0; i < m; ++i) {
        int a, b;
        cin >> a >> b;
        a--, b--;
        e[a].push_back(b);
        ingoing[b]++;
    }

    queue<int> noIngoing;
    for (int i = 0; i < n; ++i)
        if (ingoing[i] == 0)
            noIngoing.push(i);

    int res = 0;
    while (!noIngoing.empty()) {
        if (nextEdge[noIngoing.front()] == e[noIngoing.front()].size()) {
            noIngoing.pop();
            continue;
        }

        res++;
        int current = noIngoing.front();
        while (nextEdge[current] < e[current].size()) {
            nextEdge[current]++;
            current = e[current][nextEdge[current] - 1];
            ingoing[current]--;
            if (ingoing[current] == 0)
                noIngoing.push(current);
        }
    }

    cout << res << "\n";
}

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: ACCEPTED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: ACCEPTED