leetcode

Permutations

Given a collection of distinct numbers, return all possible permutations.

For example,
[1,2,3] have the following permutations:

[  [1,2,3],  [1,3,2],  [2,1,3],  [2,3,1],  [3,1,2],  [3,2,1]]

Solution:

  public List<List<Integer>> permute(int[] nums) {        List<List<Integer>> list = new ArrayList<>();        backtrack(list, new ArrayList<>(), nums);        return list;    }    private void backtrack(List<List<Integer>> list, List<Integer> tempList, int[] nums) {        if (tempList.size() == nums.length) {            list.add(new ArrayList<>(tempList));        } else {            for (int i = 0; i < nums.length; i++) {                if (tempList.contains(nums[i]))                    continue;                tempList.add(nums[i]);                backtrack(list, tempList, nums);                tempList.remove(tempList.size() - 1);            }        }    }