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<>>
     */
    static public ArrayList<ArrayList<Integer>> permute (int[] num) {
        int[] v = new int[num.length];
        ArrayList<ArrayList<Integer>> result = new ArrayList<>();
        List<Integer> list = new ArrayList<>();
        dfs(num, v, result, list);
        return result;
    }

    static public void dfs(int[] num, int[] v, ArrayList<ArrayList<Integer>> result,
                           List<Integer> list) {
        if (list.size() == num.length) {
            result.add(new ArrayList<>(list));
            return;
        }
        for (int i = 0; i < num.length; i++) {
            if (v[i] == 0) {
                list.add(num[i]);
                v[i] = 1;
                dfs(num, v, result, list);
                list.remove(list.size() - 1);
                v[i] = 0;
            }
        }
    }
}