Detect Cycle using BFS with khans Algorithm.cpp

#include <bits/stdc++.h>

using namespace std;
const int N = 1e5;
vector<int>adj_list[N];
int visited[N], inDegree[N];
int n, m;


bool detect_cycle(int node) {
    queue<int>q;
    for (int i = 1; i <= n; i++) {
        if (inDegree[i] == 0) {
            q.push(i);
        }
    }
    int count = 0;
    while (!q.empty())
    {
        int u = q.front();
        q.pop();
        count++;
        for (int i = 0; i < adj_list[u].size(); i++) {
            int v = adj_list[u][i];
            inDegree[v]--;
            if (inDegree[v] == 0) {
                q.push(v);
            }
        }
    }

    if (count != n) {
        return true;
    }
    else {
        return false;
    }

}



int main() {

    cin >> n >> m;
    for (int i = 0; i < m; i++) {
        int u, v;
        cin >> u >> v;
        adj_list[u].push_back(v);
        inDegree[v]++;
    }

    bool got_cycle = detect_cycle(1);
    if (got_cycle) {
        cout << "Cycle Exist" << endl;
    }
    else {
        cout << "Cycle doesn't exist" << endl;
    }
}

/*
Input:
4 5
1 3
1 2
2 3
3 4
4 2
---------
4 4
1 2
1 3
2 4
3 4
---------
5 4
1 2
2 4
4 3
3 5
5 4
 */

This Code I have write with the help of this video: https://youtu.be/G1HuCjgvJb0