Day27 全排列-CFANZ编程社区

Day27 全排列

给定一个没有重复数字的序列，返回其所有可能的全排列

https://leetcode-cn.com/problems/permutations/

示例1：

Java解法

package sj.shimmer.algorithm.ten_3;

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

/**
 * Created by SJ on 2021/2/20.
 */

class D27 {
    public static void main(String[] args) {
        System.out.println(permute(new int[]{1, 2, 3}));
    }

    public static List<List<Integer>> permute(int[] nums) {
        List<List<Integer>> lists = new ArrayList<>();
        List<Integer> list = new ArrayList<>();
        for (int num : nums) {
            list.add(num);
        }
        create(lists, list, nums.length, 0);
        return lists;
    }

    public static void create(List<List<Integer>> lists, List<Integer> list, int length,int index) {
        if (index>= length) {
            lists.add(new ArrayList<>(list));
            return;
        }
        for (int i = index; i < length; i++) {
            Collections.swap(list,index,i);
            create(lists, list,length,index+1);
            Collections.swap(list,i,index);
        }
    }
}