dfs（JAVA）

import java.util.Scanner;public class Main {static int maxn = 200;static boolean[] f = new boolean[maxn];static boolean[][] a = new boolean[maxn][maxn];static int n, m;static void dfs(int v) {f[v] = true;for (int i = 1; i <= n; i++) {if (!f[i] && a[v][i]) {dfs(i);System.out.print(i + "  ");}}}public static void main(String[] args) {Scanner in = new Scanner(System.in);n = in.nextInt();m = in.nextInt();for(int i = 0; i < m; i++) {int x = in.nextInt();int y = in.nextInt();a[x][y] = true;}dfs(1);}}