Find a cycle in directed graph

Acylicity.java

import java.util.ArrayList;
import java.util.PriorityQueue;
import java.util.Scanner;
import java.util.Stack;

public class Acyclicity {

    private static int acyclic(ArrayList<Integer>[] adj) {
        //write your code here
        boolean[] visited = new boolean[adj.length];
        Stack<Integer> vStack = new Stack<>();
        for (int v = 0; v < adj.length; v++) {
            if (visited[v]) {
                continue;
            }
            visited[v] = true;
            vStack.push(v);
            while(!vStack.isEmpty()) {
                int x = vStack.pop();
                for (Integer u: adj[x]) {
                    if (u == v) {
                        return 1;
                    }
                    if (visited[u]) {
                        continue;
                    }
                    visited[u] = true;
                    vStack.push(u);
                }
            }
        }
        return 0;
    }

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        int m = scanner.nextInt();
        ArrayList<Integer>[] adj = (ArrayList<Integer>[])new ArrayList[n];
        for (int i = 0; i < n; i++) {
            adj[i] = new ArrayList<Integer>();
        }
        for (int i = 0; i < m; i++) {
            int x, y;
            x = scanner.nextInt();
            y = scanner.nextInt();
            adj[x - 1].add(y - 1);
        }
        System.out.println(acyclic(adj));
    }
}