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):
"123""132""213""231""312""321"
Given n and k, return the kth permutation sequence.
1 public class Solution { 2 public String getPermutation(int n, int k) { 3 int num[] = new int [n]; 4 int permu = 1; 5 for(int i=0;i<n;i++){ 6 num[i]=i+1; 7 permu *= i+1; 8 } 9 k--; 10 StringBuilder sb =new StringBuilder(); 11 for(int i=0;i<n;i++){ 12 permu /=n-i; 13 int selected = k/permu; 14 sb.append(num[selected]); 15 k %= permu; 16 for(int j=selected+1;j<n;j++){ 17 num[j-1] = num[j]; 18 } 19 } 20 return sb.toString(); 21 } 22 }