[LeetCode 60] Permutation Sequence

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 kth permutation sequence.

Note: Given n will be between 1 and 9 inclusive.

Diffculty
Medium

Similar Problems
[LeetCode ] Next Permutation Medium [LeetCode ] Permutations Medium

Analysis

这题很明显需要用到 backtrack 思路、

主要有两种方式

1、处理某个元素后，把其从原数组中删除 2、处理某个元素时，通过 swap 把它放在每次要递归的那部分数组的首位

方法一

方法二