Permutation Of Array problem leetCode

 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]]

 

class Solution {
    public List<List<Integer>> permute(int[] nums) {
        List<List<Integer>> result = new ArrayList<>();
        generatePermutations(nums, 0, result);
        return result;
    }

    private void generatePermutations(int[] nums, int start, List<List<Integer>> result) {
        if (start == nums.length) {
            result.add(convertToList(nums)); // Convert array to list and add to result
            return;
        }
        for (int i = start; i < nums.length; i++) {
            swap(nums, start, i);
            generatePermutations(nums, start + 1, result);
            swap(nums, start, i); // Backtrack
        }
    }

    private List<Integer> convertToList(int[] nums) {
        List<Integer> list = new ArrayList<>();
        for (int num : nums) {
            list.add(num);
        }
        return list;
    }

    private void swap(int[] nums, int i, int j) {
        int temp = nums[i];
        nums[i] = nums[j];
        nums[j] = temp;
    }
}

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