摘要:
Given a non-empty binary tree, find the maximum path sum. For this problem, a path is defined as any sequence of nodes from some starting node to any 阅读全文
摘要:
Given a string containing only digits, restore it by returning all possible valid IP address combinations. Example: ip地址恢复 ip地址根据.分成4部分,每个部分都小于255. 编码 阅读全文
摘要:
Given an integer n, return 1 - n in lexicographical order. For example, given 13, return: [1,10,11,12,13,2,3,4,5,6,7,8,9]. Please optimize your algori 阅读全文
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Median is the middle value in an ordered integer list. If the size of the list is even, there is no middle value. So the median is the mean of the two 阅读全文
摘要:
Given n pairs of parentheses, write a function to generate all combinations of well-formed parentheses. For example, given n = 3, a solution set is: [ 阅读全文