46. Permutations

难度: Medium

题目描述

Given an array nums of distinct integers, return all the possible permutations. You can return the answer in any order.

 

Example 1:

Input: nums = [1,2,3]
Output: [[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]]

Example 2:

Input: nums = [0,1]
Output: [[0,1],[1,0]]

Example 3:

Input: nums = [1]
Output: [[1]]

 

Constraints:

• 1 <= nums.length <= 6
• -10 <= nums[i] <= 10
• All the integers of nums are unique.

解题思路

代码实现

解决方案

java

class Solution {
    public List<List<Integer>> permute(int[] nums) {

        List<List<Integer>> result = new ArrayList<>();
        List<Integer> current = new ArrayList<>();
        getNum(result, current, nums);
        return result;

    }

    public void getNum(List<List<Integer>> result, List<Integer> current, int[] nums) {

        if (current.size() == nums.length) {
            result.add(new ArrayList<>(current));
            return;
        }

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

    }
}