Use one queue + size variable public class Solution { public ArrayList<ArrayList<Integer>> levelOrder(TreeNode root) { ArrayList result = new ArrayList(); if (root == null) return result; Queue<TreeNode> queue = new LinkedList<TreeNod…

Given a binary search tree(BST), find the lowest common ancestor of two given nodes in the BST. Node* LCA(Node* root, Node* p, Node* q) { if (!root || !p || !q) return NULL; if (max(p->data, q->data) < root->data) return LCA(root->left, p,…

1099 Build A Binary Search Tree(30 分) A Binary Search Tree (BST) is recursively defined as a binary tree which has the following properties: The left subtree of a node contains only nodes with keys less than the node's key. The right subtree of a nod…

UVA 1264 - Binary Search Tree 题目链接 题意:给定一个序列,插入二叉排序树,问有多少中序列插入后和这个树是同样的(包含原序列) 思路:先建树,然后dfs一遍,对于一个子树而言,仅仅要保证左边和右边顺序对就能够了,所以种数为C(左右结点总数,左结点),然后依据乘法原理乘上左右子树的情况就可以 代码: #include <cstdio> #include <cstring> typedef long long ll; const int MAXNODE =…

(http://leetcode.com/2010/11/convert-sorted-list-to-balanced-binary.html) Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST. Code: BinaryTree* sortedListToBST(ListNode *& list, int start, int…

(http://leetcode.com/2010/11/convert-sorted-array-into-balanced.html) Given an array where elements are sorted in ascending order, convert it to a height balanced BST. Code: BinaryTree* sortedArrayToBST(int arr[], int start, int end) { if (start > en…

(http://leetcode.com/2010/11/convert-binary-search-tree-bst-to.html) Convert a BST to a sorted circular doubly-linked list in-place. Think of the left and right pointers as synonymous to the previous and next pointers in a doubly-linked list. Code: v…

Two methods: 1. Traverse 2. Divide & Conquer // Traverse: usually do not have return value public class Solution { public void traverse(TreeNode root) { if (root == null) return; traverse(root.left); traverse(root.right); } } // Divide & Conquer:…

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 nodes with keys less than the node's key. The right subtree of a node contains only nodes with keys…

题目描述: 一个二叉搜索树,给定两个节点a,b,求最小的公共祖先 _______6______ / \ ___2__ ___8__ / \ / \ 0 _4 7 9 / \ 3 5 例如: 2,8 -->6 2,4-–>2 原文描述: Given a binary search tree (BST), find the lowest common ancestor (LCA) of two given nodes in the BST. According to the definition…