求问下各位大神,怎么判断一个按照Preorder traversal serialized的binary tree的序列是否正确呢?不能deserialize成树比如 A) 9 3 4 # # 1 # # 2 # 6 # #是对的,因为表示 9 / \ 3 2 / \ \ 4 1 6 B ) 9 3 4 # # 1 # #就是错的,因为无法反构造回一棵树 我觉得可以在字符串里找"n##"这种结构(对应tree里两个children都是Null的叶节点),找到之后就把"n##&…

求string str1中含有string str2 order的 subsequence 的最小长度 DP做法:dp[i][j]定义为pattern对应到i位置,string对应到j位置时,shortest substring的长度,Int_Max表示不存在 package ShortestSubsequenceIncluding; public class Solution { public String findShortest(String a, String b){ if(a==nul…

Given preorder traversal of a binary search tree, construct the BST. For example, if the given traversal is {10, 5, 1, 7, 40, 50}, then the output should be root of following tree. 10 / \ 5 40 / \ \ 1 7 50 We have discussed O(n^2) and O(n) recursive…

给定一个二叉树,以集合方式返回其中序/先序方式遍历的所有元素. 有两种方法,一种是经典的中序/先序方式的经典递归方式,另一种可以结合栈来实现非递归 Given a binary tree, return the inorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,3,2]. OJ's Binary Tree Serialization: The s…

Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. Note: Recursive solution is trivial, could you do it iteratively? 一般我们提到树的遍历,最常见的有先序遍历,中序遍历,后序遍历和层序遍历,它们用递归实现起…

Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. /** * Definition for a binary tree node. * struct TreeNode { * int val; * TreeNode *left; * TreeNode *right; *…

Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. 二叉树的先序遍历.递归算法太简单了,重点讨论一下非递归的. 我自己写的时候一直纠结于何时弹出结点.后来看了几个版本的,发现可以跳过这个部分. 贴上我最喜欢的版本,逻辑最清楚 //我最喜欢的版本 逻辑清晰 vector<i…

Given a binary tree, return the preorder traversal of its nodes' values. For example:Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. Note: Recursive solution is trivial, could you do it iteratively? 这题简单,属于课本习题的难度,题目提示说用迭代试试,当然用递归也可以AC的.迭代的时候要…

Binary Tree Preorder Traversal Given a binary tree, return the preorder traversal of its nodes' values. For example: Given binary tree {1,#,2,3}, 1 \ 2 / 3 return [1,2,3]. Note: Recursive solution is trivial, could you do it iteratively? Solution: 递归…

Given a binary tree, return the preorder traversal of its nodes' values. Given: 1 / \ 2 3 / \ 4 5 return [1,2,4,5,3]. Thinking: For this problem, you need to think about using recursive or non-recursive methods. As recursive method, we should think t…