摘要：
超简洁的代码本来考虑是不是真的要每个点求一个maxDepth，看来是的哟public class Solution { public boolean isBalanced(TreeNode root) { if (root==null) return true; i... 阅读全文
摘要：
Given an array where elements are sorted in ascending order, convert it to a height balanced BST.题解完全抄自ref的说明，感谢！“题解：先复习下什么是二叉搜索树（引自Wikipedia）：二叉查找树（B... 阅读全文
摘要：
Given a binary tree, find its maximum depth.The maximum depth is the number of nodes along the longest path from the root node down to the farthest le... 阅读全文
摘要：
跟之前的解法一模一样Binary Tree Level Order Traversal I,II 不赘述public class Solution { public ArrayList> zigzagLevelOrder(TreeNode root) { ArrayList> r... 阅读全文
摘要：
Given a binary tree, return thelevel ordertraversal of its nodes' values. (ie, from left to right, level by level).For example:Given binary tree{3,9,2... 阅读全文
摘要：
有个问题，就是不能和same tree一样光看root 做recursive而是必须比较左右节点，因为对称是指整个树否则就会出现 1 2 2 # 3 3public class Solution { public boolean isSymmetric(TreeNode root) { ... 阅读全文
摘要：
简单题ref“使用的是先序遍历，算法的复杂度跟遍历是一致的，如果使用递归，时间复杂度是O(n)，空间复杂度是O(logn)。” by codegankerhttp://blog.csdn.net/linhuanmars/article/details/22839819•Time to search ... 阅读全文
摘要：
Two elements of a binary search tree (BST) are swapped by mistake.Recover the tree without changing its structure.Note:A solution using O(n) space is ... 阅读全文
摘要：
Given a binary tree, determine if it is a valid binary search tree (BST).Assume a BST is defined as follows:The left subtree of a node contains only n... 阅读全文
摘要：
Givens1,s2,s3, find whethers3is formed by the interleaving ofs1ands2.For example,Given:s1="aabcc",s2="dbbca",Whens3="aadbbcbcac", return true.Whens3="... 阅读全文