题解 | #没有重复项数字的全排列#

import java.util.*;


public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     *
     * @param num int整型一维数组
     * @return int整型ArrayList<ArrayList<>>
     */
    ArrayList<ArrayList<Integer>> res = new ArrayList<ArrayList<Integer>>();
    ArrayList<Integer> nums = new ArrayList<Integer>();
    public ArrayList<ArrayList<Integer>> permute (int[] num) {
        // write code here
        boolean[] vis = new boolean[num.length];
        Arrays.sort(num);
        recursion(num, vis);
        return res;
    }
    public void recursion(int[] num, boolean[] vis) {
        if (nums.size() == num.length) {
            res.add(new ArrayList<>(nums));
        } else {
            for (int i = 0; i < num.length; i++) {
                if (vis[i])continue;
                nums.add(num[i]);
                vis[i] = true;
                recursion(num, vis);
                nums.remove(nums.size()-1);
                vis[i] = false;
            }
        }
    }
}