Leetcode46.全排列

题目传输地址: ​​https://leetcode.cn/problems/permutations/submissions/​​

代码如下

//递归解法
public static List<List<Integer>> permute(int[] nums) {
        List<List<Integer>> result = new ArrayList<>();
        if(nums.length==1){
            result.add(Arrays.asList(nums[0]));
        }
        for (int i = 0; i < nums.length; i++) {
            int[] restNums = getRestNums(nums, i);
            List<List<Integer>> list = permute(restNums);
            for (List<Integer> list1 : list) {
                List<Integer> list2 = new ArrayList<>(list1);
                list2.add(nums[i]);
                result.add(list2);
            }
        }
        return result;
    }

    private static int[] getRestNums(int[] nums, int i) {
        final int[] restNums = new int[nums.length - 1];
        for (int n = 0; n < i; n++) {
            restNums[n] = nums[n];
        }
        for (int n = i + 1; n < nums.length; n++) {
            restNums[n - 1] = nums[n];
        }
        return restNums;
    }