LeetCode刷题经验总结记录--46. 全排列

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

给定一个 没有重复 数字的序列，返回其所有可能的全排列。

示例：

输入: [1,2,3]
输出:
[
  [1,2,3],
  [1,3,2],
  [2,1,3],
  [2,3,1],
  [3,1,2],
  [3,2,1]
]

解法：

package leetcode2;

import java.util.LinkedList;
import java.util.List;

/**
 * 2021/3/11 17:57
 *
 * @Author ayue
 */
public class Solution46 {
    public List> permute(int[] nums) {
        List> res = new LinkedList<>();
        boolean[] isUsed = new boolean[nums.length];
        dic(res, new LinkedList<>(), nums, 0, isUsed);
        return res;
    }
    
    private void dic(List> res, List cur, int[] nums, int depth, boolean[] isUsed) {
        //回溯+剪枝
        if (depth == nums.length) {
            res.add(new LinkedList<>(cur));
            return;
        }
        for (int i = 0; i < nums.length; ++i) {
            if (!isUsed[i]) {
                cur.add(nums[i]);
                isUsed[i] = true;
                dic(res, cur, nums, depth + 1, isUsed);
                isUsed[i] = false;
                cur.remove(cur.size() - 1);
            }
        }
    }
    
    public static void main(String[] args) {
        Solution46 solution46 = new Solution46();
        int[] nums = new int[]{1, 2, 3};
        System.out.println(solution46.permute(nums));
    }
}