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package Graph;import java.util.ArrayList;import java.util.LinkedList;import java.util.Scanner;import java.util.Stack;public class DirectedCycle {	int v, e;	boolean []visit;	boolean []onStack;	int []path;	boolean hasCycle = false;	int s;	Stack
   
     stack;	LinkedList
    
      []adj;	public static void main(String[] args) {		new DirectedCycle().run();	}	public void run() {		Scanner in = new Scanner(System.in);		v = in.nextInt();		e = in.nextInt();		visit = new boolean[v+1];		onStack = new boolean[v+1];		adj = new LinkedList[v+1];		path = new int[v];		stack = new Stack<>();		for(int i = 0; i < v; i++ ) {			adj[i] = new LinkedList<>();		}		for(int i = 0; i < e; i++ ) {			int a = in.nextInt();			int b = in.nextInt();			adj[a].offer(b);		}		for(int i = 0; i < v; i++ ) {			if(!visit[i])				dfs(i);		}		if(hasCycle)			printPath();		else {			System.out.println("No cycle!");		}	}	public void printPath() {		boolean flag = true;		while(!stack.isEmpty()) {			if(flag) {				System.out.print(stack.pop());				flag = false;			}			else				System.out.print("-" + stack.pop());		}	}	public void dfs(int cur) {		visit[cur] = true;		onStack[cur] = true;		for(int w :adj[cur]) {			if(!visit[w]) {				path[w] = cur;				dfs(w);			}			else if(onStack[w]) {				hasCycle = true;				stack.push(cur);//把结束点多入栈一次标记结束位置以区别与其他环				for(int x = cur; x != w; x = path[x])//结束点为当前第一个出现的已标记并且在栈内的点					stack.push(x);				stack.push(w);					return;			}		}		onStack[cur] = false;	}				}
    
   

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