如何使用java实现回溯算法

void backtrack(参数) {
    if (满足结束条件) {
        将当前解加入结果集;
        return;
    }

    for (选择 : 所有可选项) {
        做选择;
        backtrack(新参数);
        撤销选择;
    }
}   

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

    private void backtrack(int[] nums, List<Integer> permutation, List<List<Integer>> result) {
        if (permutation.size() == nums.length) {
            result.add(new ArrayList<>(permutation));
            return;
        }

        for (int i = 0; i < nums.length; i++) {
            if (permutation.contains(nums[i])) {
                continue;
            }
            permutation.add(nums[i]);
            backtrack(nums, permutation, result);
            permutation.remove(permutation.size() - 1);
        }
    }
}