【LeetCode】46. 全排列(回溯)

题目链接

Description

给定一个 没有重复 数字的序列，返回其所有可能的全排列。
示例:

输入: [1,2,3]
输出:
[
  [1,2,3],
  [1,3,2],
  [2,1,3],
  [2,3,1],
  [3,1,2],
  [3,2,1]
]

Code

class Solution {
    List<List<Integer>> res = new LinkedList<>();
    public List<List<Integer>> permute(int[] nums) {
        LinkedList<Integer> track = new LinkedList<>();
        backtrack(nums, track);
        return res;
    }
    public void backtrack(int[] nums, LinkedList<Integer> track){
        if(track.size() == nums.length){
            res.add(new LinkedList(track));
            return;
        }

        for(int i = 0; i < nums.length; i++){
            if(track.contains(nums[i]))
                continue;
            track.add(nums[i]);
            backtrack(nums, track);
            track.removeLast();
        }
    }
}