Convert Sorted List to Binary Search Tree
摘要：
Given a singly linked list where elements are sorted in ascending order, convert it to a height balanced BST.分析：将一个按升序排列的单链表转换成一个平衡二叉查找树，难点在于如何确定单链表的中... 阅读全文
Jump Game
摘要：
Given an array of non-negative integers, you are initially positioned at the first index of the array.Each element in the array represents your maximu... 阅读全文
Path Sum II
摘要：
Given a binary tree and a sum, find all root-to-leaf paths where each path's sum equals the given sum.For example:Given the below binary tree andsum =... 阅读全文
Count and Say
摘要：
The count-and-say sequence is the sequence of integers beginning as follows:1, 11, 21, 1211, 111221, ...1is read off as"one 1"or11.11is read off as"tw... 阅读全文
Search for a Range
摘要：
Given a sorted array of integers, find the starting and ending position of a given target value.Your algorithm's runtime complexity must be in the ord... 阅读全文
Unique Paths II
摘要：
Follow up for "Unique Paths":Now consider if some obstacles are added to the grids. How many unique paths would there be?An obstacle and empty space i... 阅读全文
Subsets
摘要：
Given a set of distinct integers,S, return all possible subsets.Note:Elements in a subset must be in non-descending order.The solution set must not co... 阅读全文
Valid Sudoku
摘要：
这道题是个细节实现题，只要把valid sudoku满足的三个条件判断一下即可。valid sudoku需满足下列三个条件：1）每一行数字1~9有且只出现一次。2）每一列数字1~9有且只出现一次。3）对于每个3*3的sub-box（用i=3、6，j=3、6两条线划分，总共9个sub-box）数字1~... 阅读全文
Longest Consecutive Sequence
摘要：
Given an unsorted array of integers, find the length of the longest consecutive elements sequence.For example,Given[100, 4, 200, 1, 3, 2],The longest ... 阅读全文
Valid Parentheses
摘要：
Given a string containing just the characters'(',')','{','}','['and']', determine if the input string is valid.The brackets must close in the correct ... 阅读全文