递归实现排列型枚举 Java

import java.util.*;
import java.io.*;

public class Main {
	static int n;
	static int[] arr; // 存放每行最终结果
	static boolean[] checked; // 标记已检查点

	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer(br.readLine());
		n = Integer.parseInt(st.nextToken());
		arr = new int[n + 1];
		checked = new boolean[n + 1];
		dfs(1); // 从1开始搜索
	}

	static void dfs(int pos) {
		if (pos > n) {
			for (int i = 1; i <= n; i++) {
				System.out.print(arr[i] + " ");
			}
			System.out.println();
            // return回溯继续搜索
		} else {
			for (int i = 1; i <= n; i++) {
				if (!checked[i]) {
					checked[i] = true;
					arr[pos] = i;
					dfs(pos + 1);
					checked[i] = false; // 重置标记状态
				}
			}
		}
	}
}

DFS模板题~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~