leetcode回溯-46

import java.util.LinkedList; import java.util.List; /** <p>给定一个不含重复数字的数组 <code>nums</code> ，返回其 <em>所有可能的全排列</em> 。你可以 <strong>按任意顺序</strong> 返回答案。</p> <p>&nbsp;</p> <p><strong>示例 1：</strong></p> <pre> <strong>输入：</strong>nums = [1,2,3] <strong>输出：</strong>[[1,2,3],[1,3,2],[2,1,3],[2,3,1],[3,1,2],[3,2,1]] </pre> <p><strong>示例 2：</strong></p> <pre> <strong>输入：</strong>nums = [0,1] <strong>输出：</strong>[[0,1],[1,0]] </pre> <p><strong>示例 3：</strong></p> <pre> <strong>输入：</strong>nums = [1] <strong>输出：</strong>[[1]] </pre> <p>&nbsp;</p> <p><strong>提示：</strong></p> <ul> <li><code>1 &lt;= nums.length &lt;= 6</code></li> <li><code>-10 &lt;= nums[i] &lt;= 10</code></li> <li><code>nums</code> 中的所有整数 <strong>互不相同</strong></li> </ul> <div><div>Related Topics</div><div><li>数组</li><li>回溯</li></div></div><br><div><li>👍 2073</li><li>👎 0</li></div> */ //leetcode submit region begin(Prohibit modification and deletion) class Solution { List<List<Integer>> res = new LinkedList<>(); public List<List<Integer>> permute(int[] nums) { backtrack(nums,new LinkedList<>()); return res; } //回溯，固定框架，类似多叉树遍历 void backtrack(int[] nums,LinkedList<Integer> track){ if(track.size()== nums.length){ res.add(new LinkedList<>(track)); return; } for (int i = 0; i < nums.length; i++) { if(track.contains(nums[i])){ continue; } track.add(nums[i]); backtrack(nums,track); track.removeLast(); } } } //leetcode submit region end(Prohibit modification and deletion)