csdnnmbdybb的博客

回溯法 import java.util.*; public class Solution { public ArrayList<String> Permutation(String str) { ArrayList<String>res = new ArrayList<>(); char[]chars ...

import java.util.ArrayList; import java.util.Collections; /** public class TreeNode { int val = 0; TreeNode left = null; TreeNode right = null; public TreeNode(int val) { thi...