题解 | #没有重复项数字的全排列#

1. 参数num，返回值void；2. 终结，path长度达到nums.length；3. 单层：访问就好啦，判断是否已在

import java.util.*;

public class Solution {
    ArrayList<ArrayList<Integer>> res = new ArrayList<ArrayList<Integer>>();
    LinkedList<Integer> path = new LinkedList<Integer>();
    public ArrayList<ArrayList<Integer>> permute(int[] num) {
        // 全排列，回溯问题
        getPermutation(num);
        return res;
    }
    
    private void getPermutation(int[] nums) {
        if (path.size() == nums.length) {
            res.add(new ArrayList(path));
        }

        for (int i = 0; i < nums.length; ++i) {
            if (path.contains(nums[i])) {
                continue;
            }
            path.add(nums[i]);
            getPermutation(nums);
            path.removeLast();
        }
    }
}