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One way to serialize a binary tree is to use pre-order traversal. When we encounter a non-null node, we record the node's value. If it is a null node, 阅读全文
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Given a non-negative integer num represented as a string, remove k digits from the number so that the new number is the smallest possible. Note: The l 阅读全文
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Given a sequence of n integers a1, a2, ..., an, a 132 pattern is a subsequence ai, aj, ak such that i < j < k and ai < ak < aj. Design an algorithm th 阅读全文
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You are given two arrays (without duplicates) nums1 and nums2 where nums1’s elements are subset of nums2. Find all the next greater numbers for nums1' 阅读全文
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Given a circular array (the next element of the last element is the first element of the array), print the Next Greater Number for every element. The 阅读全文
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Given a nested list of integers, implement an iterator to flatten it. Each element is either an integer, or a list -- whose elements may also be integ 阅读全文
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Implement the following operations of a queue using stacks. push(x) -- Push element x to the back of queue. pop() -- Removes the element from in front 阅读全文
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Implement the following operations of a stack using queues. push(x) -- Push element x onto stack. pop() -- Removes the element on top of the stack. to 阅读全文
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Implement a trie with insert, search, and startsWith methods. 题目含义：实现字典树的insert, search, 和startsWith 方法 字典树概念参考http://blog.csdn.net/u012501459/article 阅读全文
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Suppose you have N integers from 1 to N. We define a beautiful arrangement as an array that is constructed by these N numbers successfully if one of t 阅读全文