detect cycle using dfs

import java.util.List;

public class Solution {
    static class Graph {
        boolean dfs(int node, int parent, List<List<Integer>> adj, boolean[] vis) {
            vis[node] = true;

            for (int neighbor : adj.get(node)) {
                if (!vis[neighbor]) {
                    if (dfs(neighbor, node, adj, vis)) {
                        return true; // Cycle detected
                    }
                } else if (neighbor != parent) {
                    return true; // Back edge found, indicating a cycle
                }
            }

            return false; // No cycle found in this DFS traversal
        }

        boolean detectCycle(int v, List<List<Integer>> adj) {
            boolean[] vis = new boolean[v];
            for (int i = 0; i < v; i++) {
                if (!vis[i] && dfs(i, -1, adj, vis)) {
                    return true; // Cycle detected
                }
            }
            return false; // No cycle found
        }
    }
}