摘要：Given two binary trees, write a function to check if they are equal or not.Two binary trees are considered equal if they are structurally identical an... 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：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：Follow up for problem "Populating Next Right Pointers in Each Node".What if the given tree could be any binary tree? Would your previous solution stil... 阅读全文

摘要：Given a binary tree struct TreeLinkNode { TreeLinkNode *left; TreeLinkNode *right; TreeLinkNode *next; }Populate each next pointe... 阅读全文

摘要：Given a binary tree and a sum, determine if the tree has a root-to-leaf path such that adding up all the values along the path equals the given sum.Fo... 阅读全文

摘要：Given a binary tree, find its minimum depth.The minimum depth is the number of nodes along the shortest path from the root node down to the nearest le... 阅读全文

摘要：Given a binary tree, flatten it to a linked list in-place.For example,Given 1 / \ 2 5 / \ \ 3 4 6The flattened t... 阅读全文

摘要：Given an array where elements are sorted in ascending order, convert it to a height balanced BST.分析：对于BST，左右子树的高度差小于等于1，则在由sorted array构建BST时把数组中间元素作为... 阅读全文

摘要：Given a binary tree, return thebottom-up level ordertraversal of its nodes' values. (ie, from left to right, level by level from leaf to root).For exa... 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：Given a binary tree, determine if it is height-balanced.For this problem, a height-balanced binary tree is defined as a binary tree in which the depth... 阅读全文

摘要：class Solution {public: int maxPathSum(TreeNode *root) { if(root == NULL) return 0; int max_sum = INT_MIN; unordered_map node_... 阅读全文

摘要：Evaluate the value of an arithmetic expression inReverse Polish Notation.Valid operators are+,-,*,/. Each operand may be an integer or another express... 阅读全文

摘要：Givennnon-negative integers representing the histogram's bar height where the width of each bar is 1, find the area of largest rectangle in the histog... 阅读全文

摘要：Validate if a given string is numeric.Some examples:"0"=>true" 0.1 "=>true"abc"=>false"1 a"=>false"2e10"=>trueNote:It is intended for the problem stat... 阅读全文

摘要：Given an array of strings, return all groups of strings that are anagrams.Note: All inputs will be in lower-case.分析：此题的题意不是很明确，意思重新表述应该是一组string里面，有几个... 阅读全文

摘要：Given a stringSand a stringT, count the number of distinct subsequences ofTinS.A subsequence of a string is a new string which is formed from the orig... 阅读全文

摘要：Given an integer, convert it to a roman numeral.Input is guaranteed to be within the range from 1 to 3999.分析：这道题参考leetcode.pdf的解法，代码简洁，处理的巧妙。值得借鉴的几点如下... 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