蓝桥杯算法提高VIP-排列数-题解(Java代码)

import java.util.Scanner;
public class Main {
    public static int cnt = 0;
    public static int n;
    public static int[] arr = new int[10];
    public static int[] book = new int[10];
    public static void dfs(int sum) {
        if(sum == 10) {
            cnt++;
            if(cnt == n) {
                for(int i = 0;i<10;i++)
                    System.out.print(arr[i]);
            }
            return;
        }
        for(int i = 0;i<10;i++) {
            if(book[i] == 0) {
                book[i] = 1;
                arr[sum] = i;
                dfs(sum+1);
                book[i] = 0;
            }
        }
        return;
    }
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        n = sc.nextInt();
        dfs(0);
    }
}