1. Title

Permutation Sequence

2.   Http address

https://leetcode.com/problems/permutation-sequence/

3. The question

The set [1,2,3,…,n] contains a total of n! unique permutations.

By listing and labeling all of the permutations in order,

We get the following sequence (ie, for n = 3):

1. "123"
2. "132"
3. "213"
4. "231"
5. "312"
6. "321"

Given n and k, return the k^th permutation sequence.

4. My code (AC)

1     void modifyMin(char min[],int index) 2     { 3         for(int i = index; i < min.length - 1; i++) 4         { 5             min[i] = min[i+1]; 6         } 7     } 8     public String getPermutation(int n, int k) { 9 10             char str [] = new char[n];11             char min [] = new char[n];12             int base = 1;13             int layer = n-1;14             //base = (n-1)!15             min[0] = ( char ) (1 + '0');16             for(int i = 1 ; i 
     
      = 2)57                 {58                     base /= layer;59                     layer--;60                 }else{61                     base = 1;62                 }63             }64             return new String(str);65     }