LeetCode 46 Permutations（全排列问题）

package leetcode_50;

import java.util.ArrayList;
import java.util.List;


/***
 * 
 * @author pengfei_zheng
 * 给定数组元素均不相同，求出所有全排列
 */
public class Solution46 {
    public static List<List<Integer>> permute(int[] nums) {
        List<List<Integer>> list = new ArrayList<>();
        prem(list,new ArrayList<>(),nums,new boolean[nums.length]);
        return list;
    }

    private static void prem(List<List<Integer>> list, List<Integer> tempList, int[] nums, boolean[] used) {
        if(tempList.size()==nums.length){
            list.add(new ArrayList<>(tempList));
        }
        else{
            for(int i = 0; i < nums.length; i++){
                if(used[i] || i>0 && nums[i]==nums[i-1] && !used[i-1]) continue;
                used[i]=true;
                tempList.add(nums[i]);
                prem(list,tempList,nums,used);
                used[i]=false;
                tempList.remove(tempList.size()-1);
            }
        }
    }
    public static void main(String[]args){
        int []nums={1,2,3};
        List<List<Integer>> list = permute(nums);
        for(List<Integer> item:list){
            System.out.println(item);
        }
    }
}