1 public class PaiLieK 2 { 3     public String getPermutation(int n, int k) 4     { 5         List<Integer> list = new ArrayList<>(); 6         List<Integer> list1 = new ArrayList<>(); 7         for(int i = 1; i <= n; i++) 8         { 9             list.add(i);10         }11 12         boolean has = true;13         first:14         for(int i = 0; i < Math.pow(10,n);i++)15         {16             for(int j = 0; j < list.size(); j++)17             {18                 if(!(i+"").contains(list.get(j)+""))19                 {20                     has = false;21                     continue ;22                 }23             }24             if(has&&list.size() == getDigits(i))25             {26                 list1.add(i);27             }28             has = true;29         }30         Integer integer=list1.get(k-1);31         return String.valueOf(integer);32     }33 34 35     public int getDigits(int i)36     {37         int count = 0;38         while(i >0)39         {40             count++;41             i /=10;42         }43         return count;44     }45     @Test46     public void testGetDigits()47     {48         System.out.println(getDigits(198));49         getDigits(198);50     }51     @Test52     public void testGetPermutation()53     {54         String permutation = getPermutation(3, 4);55         System.out.println(permutation);56     }57 58 }